Porcelain composition, composite material comprising catalyst and ceramic, film reactor, method for producing synthetic gas, apparatus for producing synthetic gas and method for activating catalyst

ABSTRACT

A porous catalyst layer containing mixed conducting oxide is contiguous to a second surface ( 1   a ) of a selective oxygen-permeable dense continuous layer ( 1 ) containing mixed conducting oxide. A porous intermediate catalyst layer ( 3 ) containing mixed conducting oxide is contiguous to a first layer ( 1   b ) of the dense continuous layer ( 1 ). A porous reactive catalyst layer ( 4 ) provided with a metal catalyst and a support is contiguous to the porous intermediate catalyst layer ( 3 ) in a manner to sandwich between the dense continuous layer ( 1 ) and the porous reactive catalyst layer ( 4 ).

TECHNICAL FIELD

[0001] The present invention relates to a ceramic composition, compositematerial of catalyst and ceramics, membrane reactor, production methodfor synthetic gas, production apparatus for the synthetic gas and methodfor activating the catalyst suitable for a partition membrane reactorwhich can conduct an industrial selective permeation and separationprocess for oxygen, oxidation reaction or partial oxidative reaction ofhydrocarbon gas molecule in a single apparatus.

BACKGROUND ART

[0002] Conventionally, separation of oxygen from oxygen-containing gashas been an industrially important process. However, oxygen productiontechnology represented by a current low temperature distillation systemis capital intensive and energy-guzzling, and though there is someprogress in technical improvement in process configuration and the like,it is basically a separation technology based on an extremely smalldifference between boiling points of oxygen and nitrogen, which makes itdifficult to achieve a substantial cost reduction.

[0003] Under these circumstances, as a new stream of the oxygenproduction technology, a high temperature (up to 900° C.)oxygen-separation technology utilizing a dense mixed conductive ceramicmembrane as a use of oxide ion mixed conductor described above hasattracted much attention in recent years. Research and development ofthe high temperature oxygen-separation technology has been rapidlyactivated particularly in the western countries. Further, it has apossibility to lead to energy-saving with compact equipment.

[0004] In the dense mixed conductive ceramic membrane, oxygen ions andelectrons are selectively transferred passing through a dense ceramicmembrane material which does not permeate other chemical sorts(nitrogen, water, carbon dioxide, and so on). The oxygen ion bonds withan electron coming from the opposite side (anode side) of the membraneon a surface (cathode side) of the dense ceramic membrane to generateoxygen ion. The oxygen ion diffusedly moves in the dense membraneaccording to the difference in chemical potential of the oxygen ion andrelease the electron on the anode side to be oxygen molecule again. Atthis time, the electron moves in the opposite direction of the oxygenion to keep electric neutrality.

[0005] A technology of reforming hydrocarbon-containing gas such asmethane or the like as a raw material into hydrogen or synthetic gas(mixed gas of carbon monoxide and hydrogen) has assumed an importantposition in petroleum chemical process. This reforming technology iscombined with a technology to produce synthetic liquid fuel usinghydrocarbon-containing gas such as methane and the like as a rawmaterial (Gas-To-Liquids: GTL) or progress of a fuel cell technology,and research and development activities at home and abroad for theabove-described technology have been stepping up remarkably in recentyears, because the former leads to “effective use of unused natural gasresources and the like” and “supply of a clean energy source friendly tothe global environment” and the latter leads to “installment on a cleanvehicle”, “widespread use of distributed power source”, and “use ofclean energy”.

[0006] Under these circumstances, research of using the dense mixedconductive ceramic membrane for not only separation of oxygen fromoxygen-containing gas such as air and the like, but also for a reformingreactor has been accelerated recently. In the membrane reformingreactor, air is passed through one side (cathode side) of the membrane,and a catalyst is disposed on the opposite side (anode side) thereof tolet hydrocarbon gas such as methane or the like flow to cause a partialoxidative reaction (oxygen is consumed). A reforming catalyst forhydrocarbon is contiguous with the surface of a partition membrane onthe raw material gas side (anode side) containing hydrocarbon. On theair side or raw material gas side (cathode side) containing oxygen ofthe partition membrane, separation of oxygen molecule and ionizationreaction take place and oxygen component in the gas changes to oxygenion which is caught into the partition membrane. The oxygen ion diffusesfrom the cathode side to the anode side according to chemical potentialgradient of oxygen in the partition membrane and partial oxidativereaction of hydrocarbon component on the anode side of the partitionmembrane occurs. Electron flow in the opposite direction to oxygen ionflow, and ionize oxygen elements on the cathode side. Generally, about900° C. is adopted as an operation temperature of the reforming reactor.This is because high temperatures of 800 to 900° C. or more are usuallyrequired to display a state that dense mixed conductive ceramic materialelectrically conducts both oxygen ions and electrons sufficiently, inother words, to display high mixed conductivity. With this method,oxygen permeated through the membrane is consumed at once to make apartial pressure of oxygen (chemical potential of oxygen) on the anodeside extremely small by a partial oxidative reaction of hydrocarbon, sothat difference in chemical potential of oxygen (difference in partialpressure of oxygen), namely a driving force of selective oxygenpermeation in the partition membrane eventually becomes remarkablylarge. Accordingly, an oxygen permeation rate, namely, a partialoxidative reaction rate can be made large. Further, since a partialoxidative reaction of methane and the like can be conducted togetherwith air separation at the same time, in other words, since bothseparation of oxygen and an oxidation reaction can be performedsimultaneously in a single unit, it may result in a compact andinexpensive reactor.

BACKGROUND ART RELATING TO A FIRST INVENTION

[0007] In order to bring such a selective permeation and separationprocess of oxygen, or partition membrane reactor, and the like into apractical use, materials having high oxide ion conductivity arerequired. As a material to satisfy the requirement, oxide ion mixedconductor having a perovskite structure is being studied. The perovskitestructure is a crystal structure in which cations occupy A site where 12pieces of anionic oxygen are coordinated and B site where 6 pieces ofoxygen are coordinated respectively. Many of the materials studied forthe above-described object contain Co or Fe in B site.

[0008] For instance, ceramic compositions such as(La_(x)Sr_(1−x))CoO_(3−α), (x is in the range of 0.1 to 0.9, α is 0 to0.5), which is disclosed in Japanese Patent Application Laid-open No.Sho 56-92103, (La_(1−x)Sr_(x))(Co_(1−y)Fe_(y))O_(3−δ) (x is in the rangeof 0.1 to 1.0, y is 0.05 to 1.0, δ is 0.5 to 0), which is disclosed inJapanese Patent Application Laid-open No. Sho 61-21717, and so on areknown as a useful leading top-rated materials. Further, in JapanesePatent Application Laid-open No. Hei 6-206706, proposed is an oxide iontransfer permeable membrane having an extremely wide composition rangecomposed of A_(x)Ba_(x)·B_(y)B′_(y)·B″_(y)·O_(3−z) (A is selected from agroup consisting of a first, second, and third families in a periodictable and a lanthanoid family of f period adopted by ICUPA, and B, B′,and B″ are selected from transition metals of d period. Further, thefollowing conditions of 0≦x≦1, 0<x′≦1, 0<y≦1, 0≦y′≦1, 0≦y″≦1, x+x′=1,y+y′+y″=1, are satisfied and z is a value determined when electriccharge of the composition is neutral). As the concrete examples for theabove, La_(0.2)Ba_(0.8)Co_(0.8)Fe_(0.2)O_(2.6), and the like are given.

[0009] Y.Teraoka et al. studied an oxygen permeation rate of perovskitestructure oxides expressed by a composition formula ofLa_(0.6)A′_(0.4)Co_(0.8)Fe_(0.2)O_(3−δ) and pointed out in ChemistryLetters, pp. 503-506, 1988 that the oxygen permeation rate could beimproved by containing Ba in A site of the perovskite structure. Whenconsidering this knowledge expandedly, it can be expected thatimprovement of the oxygen permeation rate of the perovskite structuremixed conductor oxides can be realized by substituting Sr or La whichare often used as an element placed in A site of the perovskitestructure oxides of mixed conductors for Ba as mush as possible.Especially, substitution of La having a valence of 3 for Ba having avalence of 2 leads to increase of oxygen holes in a crystal which is acarrier of oxygen permeation, and an effect of “killing two birds withone stone” is expected as a measure for improvement of the oxygenpermeation rate.

[0010] However, as shown in “Perovskite related compounds” Kikan Kagakusosetsu, No.32 (1997), pp. 11-13, edited by Chemical Society of Japan,it is known that when A site of perovskite is replaced from Sr having asmall ion radius to Ba having a large ion radius, a structure having aBaNiO₃ type or the like becomes more stable than the perovskitestructure and easier to appear. It is shown by an actual preliminaryexperiment carried out by the inventors that though the crystalsstructure of a sintered body of SrCo_(0.8)Fe_(0.2)O_(3−δ) was a cubicperovskite structure, in BaCo_(0.8)Fe_(0.2)O_(3−δ), a phase of lowoxygen permeation rate different in crystal structure from theperovskite structure was found. This different phase is belonged to ahexagonal 12H-BaCoO_(3−x) type structure, reported by A. J. Jacobson etal. in J. Solid State Chemistry, vol.35 (1980) pp.334-340, which issimilar structure to BaNiO₃ type.

[0011] Similarly, a La_(0.2)Sr_(0.8)CoO_(3−δ) sintered body has a cubicperovskite structure while La_(0.2)Ba_(0.8)CoO_(3−δ) has fallen into a12H-BaCoO_(3−x) type structure. Conventionally, Y has been recognized asan element to substitute for La in A site of the perovskite as Masanneket al. disclosed in Japanese Patent Application Laid-open No. Hei6-56428. However, as a result that the present inventors synthesized acomposition containing Y in A site and having a large ratio of Ba, suchas Ba_(0.8)Sr_(0.1)Y_(0.1)CoO_(3−δ), and studied the structure, a stableperovskite structure could not be obtained. H. W. Brinkman studiedBaCo_(0.95)Y_(0.05)O_(3−δ) which substituted Y in B site, and reportedthat the crystal structure was BaCoO_(3−x) type hexagonal as expected,in Solid State Ionics, Vol.68(1994)PP.173-176. As described above,substitution by Ba in A site was reconfirmed as a factor to make theperovskite structure unstable.

[0012] As mentioned above, different phase such as BaNiO₃ type or itsanalogous structure is extremely low in oxygen permeation rate,materials showing these phases cannot be used in an oxygen-separationapparatus or the like. In other words, when the oxygen permeation rateis intended to be improved by increasing Ba ratio by substituting Ba forLa or Sr in A site in conventional oxide ion mixed conductor materialsuch as (La_(1−x)Sr_(x)) (Co_(1−y)Fe_(y))O_(3−δ), it used to have adilemma that stability of a cubic perovskite structure becomesinsufficient, and a different phase such as BaNiO₃ type is appeared tomake the oxygen permeation rate rather low.

BACKGROUND ART RELATING TO A SECOND INVENTION

[0013] A process of oxygen permeating through the ceramic membrane canbe evaluate by dividing the process into three processes ofdecomposition reaction of oxygen molecule into oxygen ion (cathodicreaction), a diffusion transfer depending on a chemical potentialdifference of oxygen ion, a reaction of oxygen ion into an oxygenelement and/or oxygen molecule and further oxidizing hydrocarbon (anodicreaction). Improvement of the oxygen permeation rate per unit arearequires to rate up these three processes in co-ordination with eachother. Otherwise, any of the aforementioned processes serves as arate-determining step, a high oxygen permeation rate as a whole cannotbe obtained. For instance, it would be an effective measure forincreasing diffusion transfer rate of oxygen ion in the membrane to makethe dense mixed conductive ceramic material membrane thin, but, on theother hand, the rate of cathodic reaction and/or anodic reaction come(s)to control whole oxygen permeation process with a certain thickness orbelow thereof so that an effect of increasing oxygen permeation rate bydecreasing of membrane thickness cannot be obtained. Therefore, in orderto obtain much higher oxygen permeation rate, not only thinning of adense portion, but also improvement of cathodic and anodic reactionrates becomes an important problem.

[0014] For this problem, WO98/41394 discloses a technology relating to athree-layer structured composite material of catalyst and ceramics, inwhich a porous layer using analogous material to dense ceramic materialto promote cathodic reaction by increasing of surface area, is added tothe side of oxygen-containing gas such as air of the dense mixedconductive ceramic membrane which is used for producing synthetic gas bya partial oxidative reaction of hydrocarbon such as methane or the like,and a partial oxidation catalyst is put contiguously to the oppositeside surface. However, there is no concrete description concerning astructure and material composition of a layer to serve as a partialoxidation catalyst. The present inventors used, in trial, a catalystlayer having an oxide support to support a metal catalyst as a partialoxidation catalyst layer, a dense membrane and a mixed conducting oxideas a porous layer, letting methane gas flow in the catalyst layer sideand letting air flow in the porous layer side, and oxygen permeationrate (calculated from partial oxidative reaction rate) of three-layeredstructure described in WO98/41394 was measured to find the oxygenpermeation rate being not large, and a room for further improvement in amaterial structure to obtain a high oxygen permeation rate.

[0015] Japanese Patent Application Laid-open No. Hei 7-240115 disclosesa three to four layered structure ion transfer membrane which applies asingle-layered oxygen dissociating catalyst to promote a cathodicreaction on a first surface of a membrane consisting of a close-packed(dense) multi-component metallic oxide layer by coating, and allows asingle-layered or a multi-layered porous layer consisting of mixedconductive multi-component metallic oxide or substance not exhibitingmixed conductivity according to operational conditions of the process,to be contiguous on a second surface, for the purpose of promoting ananodic reaction and adding mechanical strength to the dense membrane.Japanese Patent Application Laid-open No. Hei 7-240115 is an inventionintending mainly to develop a separating technology of oxygen fromoxygen-containing gas such as air and the like, and “oxidation oforganic compounds containing hydrocarbon” is described as a usage of theaforementioned ion transfer membrane in a paragraph [0015] and claim 46of the specification thereof. In the aforementioned ion transfermembrane, a reactive catalyst prepared by including a metallic catalystand a support in a porous layer or MC porous layer (a porous layer ofmixed conductive multi-component metallic oxide) is not included at all.More concretely, materials cited in claims as composing theabove-described porous layer are multi-component metallic oxide, metalalloy reacting with oxygen at high temperatures, zirconia forstabilizing metallic oxide, ceria, alumina which does not conductelectron or oxygen, magnesia, and so on, and a reactive catalyst formedwith a metallic catalyst and a support is not included. Besides,materials forming MC porous layer are multi-component metallic oxidesand a reactive catalyst composed of a metallic catalyst and a support isnot included either. Japanese Patent Application Laid-open No. Hei7-240115 should be thought basically to be an invention defining astructure of an ion transfer membrane promoting a cathode side and/oranode side reaction(s), and claims a very wide range of materialsforming an ion transfer membrane. However, since explanation for thereason is not enough, it is practically impossible to concretely selectthe material based on the specification in question or by simple testexcept the case described in the embodiments even for a person skilledin the art. The present inventors used, in trial, a mixed conductivemulti-component metallic oxide (the same as the mixed conducting oxidein the composition described in claim 4 of the present specification) asa porous layer contiguous to a dense membrane and a second surface ofthe membrane, and a oxide support holding metal catalyst layer (the sameas the porous reactive catalyst layer described in claim 5 of thepresent specification) as a catalyst layer contiguous to a first surfaceof the membrane, letting methane gas flow in the second surface side andair flow in the first surface side so that the ion transfer membraneworks in a manner that “supply gas containing oxygen comes into contactwith a catalyst surface of the membrane” as described in paragraph[0015], and oxygen permeation rate (calculated from oxidation reactionrate) was measured. As a result, it was found that the oxygen permeationrate was not large and there was a plenty of room for improvement inmaterial structure. It should be noted that in the case of changing thegas flow, that is, letting methane gas flow in the first surface sideand letting air flow in the second surface side, the result was the sameas what the present inventors conducted for the aforementionedWO98/41394, and there found still a room for improvement in materialstructure as already explained.

[0016] As described above, as for a membrane-type synthetic gasproduction technology from hydrocarbon and oxygen-containing gasrelating to the present invention using a composite material of catalystand ceramics, though only a common membrane structure promoting acathodic and/or anodic reaction has been disclosed, but concretetechnology for a composite material of catalyst and ceramics to createpartial oxidative reaction of hydrocarbon in a stable manner whilepromoting both cathodic and anodic reactions, and to obtain asufficiently high oxygen permeation rate for practical use has not beendisclosed, and a room for improvement is still remained.

BACKGROUND ART RELATING TO A THIRD INVENTION

[0017] In order to industrialize a membrane reforming reactor, anabsolutely necessary condition is establishment of a basic technology tobe able to conduct synthetic gas production in a stable manner whileobtaining a high oxygen permeation rate by a suitable combination of adense mixed conductive ceramic membrane and a methane (or hydrocarbon)reforming catalyst which are basic component materials, and appropriateadjustment of reaction conditions. Concerning this basic technology,WO99/21649 discloses a method of arranging a methane-reforming catalyst,catalyst materials for the same, and ceramic membrane materials.Further, U.S. Pat. No. 6,033,632 discloses ceramic membrane materialsand methane-reforming catalyst materials. These technologies arecharacterized by using materials having a very high reduction-resistancefor a dense ceramic membrane, and by using a catalyst material highlycompatible with the aforementioned materials.

[0018] Before conducting the present invention, the present inventorsprepared a dense ceramic membrane material having the thickness of alittle less than 1 mm described in WO99/21649 or U.S. Pat. No. 6,033,632and confirmed that it easily cracks and splits. Further, the oxygenpermeation rate measurement was conducted by putting a methane-reformingcatalyst contiguous to a dense ceramic membrane which did not crack orsplit and feeding air and methane, and cleared experimentally that theoxygen permeation rate was low and the crack or split was easily broughtabout during the experiment. In other words, it was experimentallyconfirmed that a practical oxygen permeation rate could not be obtainedwith the material described in these documents without setting thethickness of the dense ceramic membrane to be 0.1 mm or less, and thecrack and split were easily brought about not only during thepreparation stage but also during the experiment. Since a dense ceramicmembrane of 0.1 mm or less in thickness is too small in mechanicalstrength and not usable as a self-supporting membrane, it is required tobe used by covering it on a porous substrate. However, it is extremelydifficult to produce a porous substrate having a sufficient mechanicalstrength, and being small in flow resistance of gas components withinholes using materials easily causing crack or split, and to covereconomically a dense ceramic membrane on a porous substrate rich inpores and small in flow resistance of gas.

[0019] On the other hand, formation of a dense ceramic membrane using amaterial easily permeable for oxygen and low in reduction-resistance,using a material in which a reasonable amount of Co is contained in Bsite of a compound, for instance, having a perovskite structure has beenlong conducted. However, sufficient study has not been made in the pastfor a combination of a dense ceramic membrane material and amethane-reforming catalyst material, and a method of disposing acatalyst for it. In other words, a suitable concrete combination ofmaterials to conduct production of synthetic gas based on a high oxygenpermeation rate with a long term stability under conditions ofmethane-containing gas pressure from low to high, a method of disposinga catalyst, appropriate adjustment of the reaction conditions dependingon these items are inevitable for a practical synthetic gas productionmethod. However, these technologies have not yet been disclosed.

SUMMARY OF THE INVENTION

[0020] A first object of the present invention is to provide a ceramiccomposition which is high in rate of Ba in A site in a perovskite oxideion mixed conductor, and at the same time, a cubic perovskite phase issufficiently stable, and showing a high oxygen permeation rate.

[0021] A second object of the present invention is to provide acomposite material of catalyst and ceramics, and a membrane reactor,which are used for a membrane reactor to produce synthetic gas fromoxygen-containing gas and hydrocarbon as raw materials, to createpartial oxidative reaction of hydrocarbon in a stable manner whilepromoting both cathodic and anodic reactions, and to obtain oxygenpermeation rate higher than that in prior art.

[0022] A third object of the present invention is to provide a compositematerial of catalyst and ceramics, a production method for syntheticgas, a production apparatus for the synthetic gas, and a method ofactivating the catalyst to produce synthetic gas with high energyefficiency, at low cost, and in a stable manner for a long period.

[0023] A first ceramic composition according to the present invention isa ceramic composition of oxide ion mixed conductor having asubstantially perovskite structure, containing: Ba; at least one kind ofelement selected from a first group consisting of Co, and Fe; and atleast one kind of element selected from a second group consisting of In,Sn and Y, in which the element selected from the second group isarranged in B site of the perovskite structure.

[0024] A second ceramic composition according to the present inventionis a ceramic composition of oxide ion mixed conductor having asubstantially perovskite structure, expressed by the followingcomposition formula (formula 1).

(Ba_(rbal)XA_(1−rbal))_(α)(XB_(1−rc−rd−re−rf)XC_(rc)XD_(rd)XE_(re)XF_(rf))O_(3−δ)  (formula1)

[0025] (Where XA denotes at least one kind of element selected from athird group consisting of Sr, Ca and lanthanoide; XB denotes at leastone kind of element selected from a first group consisting of Co and Fe;XC denotes at least one kind of element selected from a second groupconsisting of In, Y, and Sn; XD denotes at least one kind of elementselected from a fourth group consisting of Nb, Ta, Ti, and Zr; XEdenotes at least one kind of element selected from a fifth groupconsisting of Cu, Ni, Zn, Li and Mg; and XF denotes at least one kind ofelement selected from a sixth group consisting of Cr, Ga, and Al. As forthe range of rbal, when XC contains only In, it fulfills the conditionof 0.4≦rba1≦1.0; when XC contains only Y, it fulfills the condition of0.5≦rba1≦1.0; when XC contains only Sn, it fulfills the condition of0.2≦rba1≦1.0; and when XC contains two or more elements composing thesecond group, it fulfills the condition of 0.2≦rba1≦1.0. As for therange of rc, when XC contains only Y, it fulfills the condition of0.06≦rc≦0.3; when XC contains at least any one of In or Sn, it fulfillsthe condition of 0.02≦rc≦0.3. The range of rd fulfills the condition of0≦rd≦0.2; the range of re fulfills the condition of 0≦re≦0.2; the rangeof rf fulfills the condition of 0≦rf≦0.2; the range of α fulfills thecondition of 0.9≦α≦1.1; and δ is a value determined to fulfill thecondition of neutral electric charge.)

[0026] A first composite material of catalyst and ceramics of thepresent invention includes: a selective oxygen-permeable densecontinuous layer containing a mixed conducting oxide; a porousintermediate catalyst layer containing a mixed conducting oxidecontiguous to a first surface of the dense continuous layer; a porousreactive catalyst layer containing a metal catalyst and a catalystsupport, contigueous to the porous intermediate catalyst layer in amanner to sandwich the porous intermediate catalyst layer between thedense continuous layer and the porous reactive catalyst layer; and aporous catalyst layer containing a mixed conducting oxide, contiguous toa second surface of the dense continuous layer.

[0027] A membrane reactor according to the present invention includes acomposite material of the above-described catalyst and ceramics.

[0028] A second composite material of catalyst and ceramics according tothe present invention includes: a dense ceramic membrane containingoxygen ion-electron mixed conducting oxide having a crystal structure ofperovskite expressed by the following composition formula (formula 2);and a catalyst portion contiguous to a first surface of the denseceramic membrane, and containing magnesia and Ni.

(Ln_(1−rg−rba3)XG_(rg)Ba_(rba3))(XH_(rh)XI_(ri)XJ_(rj))O_(3−δ)  (formula2)

[0029] (Where Ln denotes at least one kind of element selected fromlanthanoide; XG denotes at least one kind of element selected from theseventh group consisting of Sr and Ca; XH denotes at least one kind ofelement selected from an eighth group consisting of Co, Fe, Cr, and Ga,in which the sum total of the number of moles of Cr and Ga is 0 to 20%to the sum total of the number of moles of the elements composing theabove-described eighth group; XI denotes at least one kind of elementselected from a ninth group consisting of Nb, Ta, Ti, Zr, In and Y,including at least one kind of element selected from a tenth groupconsisting of Nb, Ta, In and Y; and XJ denotes at least one kind ofelement selected from an eleventh group consisting of Zn, Li and Mg. Asfor the range of rba3, when XI contains only In, it fulfills thecondition of 0.4≦rba3≦1.0, when XI contains only Y, it fulfills thecondition of 0.5≦rba3≦1.0, and when XI contains only In and Y, itfulfills the condition of 0.2≦rba3≦1.0. The range of “rg+rba3” fulfillsthe condition of 0.8≦rg+rba3≦1, the range of rh fulfills the conditionof 0<rh, the range of ri fulfills the condition of 0≦ri≦0.5, the rangeof rj fulfills the condition of 0≦rj≦0.2, and the range of “rh+ri+rj”fulfills 0.98≦rh+ri+rj≦1.02. δ is a value determined to fulfill thecondition of neutral electric charge.)

[0030] A method of producing synthetic gas according to the presentinvention includes a step of making an atmosphere, to a partitionmembrane including a dense ceramic membrane and a catalyst portioncontiguous to a first surface of the dense ceramic membrane, on thecatalyst portion side of the partition membrane a gas atmospherecontaining hydrocarbon, and atmosphere on the dense ceramic membraneside a gas atmosphere containing oxygen, in which the dense ceramicmembrane contains a perovskite structure oxygen ion-electron mixedconducting oxide whose composition is expressed by the compositionformula (formula 2), and the catalyst portion contains magnesia and Ni.

[0031] A production apparatus for synthetic gas according to the presentinvention includes a partition membrane provided with a dense ceramicmembrane having an oxygen ion-electron mixed conducting oxide whosecomposition is expressed by the composition formula (formula 2) andwhose crystal structure is perovskite, and a catalyst portion contiguousto a first surface of the dense ceramic membrane and containing magnesiaand Ni.

[0032] A method of activating a catalyst according to the presentinvention includes a step of making an atmosphere, to a partitionmembrane provided with a dense ceramic membrane whose crystal structureis perovskite, and a catalyst portion contiguous to a first surface ofthe dense ceramic membrane containing a composition expressed by thefollowing composition formula (formula 6), on the catalyst portion sideof the partition membrane a gas atmosphere containing methane whosepressure is 0.3 Mpa or more, and atmosphere on the dense ceramicmembrane side a gas atmosphere containing oxygen.

Ni_(rni)Mn_(rmn)Mg_(1−rni−rmn)O_(c)  (formula 6)

[0033] (Wherein the range of rni fulfills the condition of 0<rni≦0.4while the range of rmn fulfills the condition of 0≦rmn≦0.1. c is a valuedetermined to fulfill the condition of neutral electric charge.)

[0034] By applying the above-described ceramic composition, it ispossible to obtain a composite material, oxygen-separation apparatus,and chemical reaction apparatus for gas separation having a high oxygenpermeation rate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1 is a sectional view showing a structure of a compositematerial of catalyst and ceramics relating to a first embodiment of asecond invention;

[0036]FIG. 2 is a sectional view showing a structure of a compositematerial of catalyst and ceramics relating to a second embodiment of thesecond invention;

[0037]FIG. 3 is a sectional view showing a structure of a compositematerial of catalyst and ceramics relating to a first embodiment of athird invention;

[0038]FIG. 4 is a sectional view showing a structure of a compositematerial of catalyst and ceramics relating to a second embodiment of thethird invention; and

[0039]FIG. 5 is a sectional view showing a structure of a compositematerial of catalyst and ceramics relating to a third embodiment of thethird invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The present inventors have come up with three inventions as aresult of earnest studies to solve the above problems. A first inventionrelates to a composition formula and a crystal structure of a ceramiccomposition. A second invention relates to a four-layered compositematerial of ceramics. A third invention relates to a composition formulaof a dense ceramic membrane and a catalyst portion in a three-layeredcomposite material of ceramics. Hereinafter, the invention is roughlydivided into these three inventions, and respective preferredembodiments will be explained.

First Invention

[0041] The first invention will be explained first.

[0042] The present inventors have investigated materials which canmaintain a perovskite structure stably even when a ratio of Ba in A siteis made rich in a perovskite structure oxide ion mixed conductorcontaining Co or Fe in B site.

[0043] As a result, it was confirmed that the more the Ba, the lessstable the perovskite structure relatively. Further, it was found thateven with an element which can obtain a perovskite stabilizing effect bymaking a substitutional solid solution easily in the compositional rangeof high Sr concentration, there was possibility to arise a problem thatin the range of high Ba concentration, precipitation comes out withoutmaking the substitutional solid solution, or the perovskite stabilizingeffect cannot be obtained. Then, the range of search was expanded to acompositional range which had not been studied so much before as aperovskite structure oxide ion mixed conductor material, or acompositional range containing elements which were not effective in apositional range of high Sr concentration, and the inventors havecontinued earnest study. As a result, it was found that, in the case ofcontaining any one of In, Y or Sn, or two kinds or more out of theseelements in B site, the stabilization effect of perovskite could not beobtained in a compositional range of high Sr concentration, but thestabilization effect of perovskite was exceptionally obtained in therange of high Ba concentration.

[0044] In the case of containing In, it was found that a crystalstructure with a composition of high Ba concentration, for instance, thecrystal structure of Ba_(0.9)Sr_(0.1)Co_(0.9)In_(0.1)O_(3−δ) had a cubicperovskite structure in the temperature range from a room temperature to1000° C., and yet an oxygen permeation rate was extremely high. On theother hand, with Al and Ga which are the same group as In in theperiodic table, in the range of a high Ba ratio, such a powerfulstabilization effect of the perovskite structure could not be obtained.

[0045] In the case of containing Y, the crystal structure ofBa_(0.9)Sr_(0.1)Co_(0.9)Y_(0.1)O_(3−δ) or BaCo_(0.9)Y_(0.1)O_(3−δ) whichis a composition in which Y is in B site was found that a cubicperovskite structure is stable in a temperature range from a roomtemperature to 1000° C. or more. On further detailed studies of theseperovskite structure oxides, it was confirmed that these oxides becomelarger in lattice constant, compared with the other perovskite oxidecontaining about the same amount of Ba, for instance,Ba_(0.9)Sr_(0.1)Co_(0.9)In_(0.1)O_(3−δ). This result shows that inBa_(0.9)Sr_(0.1)Co_(0.9)Y_(0.9)O_(3−δ) and others, the reason why Yshows a powerful perovskite stabilization effect is not because Y entersinto A site by substituting for Ba or Sr which has a larger ion radiusthan Y but because it enters into B site by substituting for Co whichhas an ion radius smaller than that of Y. Further, it was found thatthis perovskite stabilization effect with Y alone requires to substituteY by 6% or more.

[0046] On the other hand, for instance, in SrCo_(0.9)Y_(0.1)O_(3−δ), adifferent phase is created, and even when Y is arranged in B site for acomposition having a rich Sr ratio, it is found that the perovskitestabilization effect is insufficient. Further, a crystal structure inwhich a lanthanoide series element which often shows an effect similarto Y, for instance, Ba_(0.9)Sr_(0.1)Co_(0.9)La_(0.1)O_(3−δ) and the likein which La or the like is arranged in B site is found to be not aperovskite structure. From the above-described result, a conclusion thatY solubilized in B site is a perovskite stabilization element workingexceptionally in the range of rich Ba ratio.

[0047] As a result of further studies, in the range of rich Ba ratio,the one containing Sn in B site is also found to have a perovskitestructure exceptionally stabilized.

[0048] Based on the new knowledge described above, compositional rangesin which the perovskite stabilization effect could be obtained withrespective elements were searched for, and further, assiduous studieswere added to compatibility with other elements, and the presentinventors finally have completed the present invention.

[0049] As clear from the above description, the point of the firstinvention is to allow the perovskite structure to exist stably in acompositional range containing high Ba ratio by arranging any one of In,Sn, or Y, or two kinds or more among them in B site in a perovskitestructure oxide ion mixed conductor containing Ba and Co and/or Fe.Among the above-described elements, in order to obtain the effect of thepresent invention, it is important for especially Y to be arranged in Bsite.

[0050] A more concrete formulation of a ceramic composition relating tothe first invention is expressed by, for instance, a composition formula(formula 1).

(Ba_(rba1)XA_(1−rba1))α(XB_(1−rc−rd−re−rf)XC_(rc)XD_(rd)XE_(re)XF_(rf))O_(3−δ)  (formula1)

[0051] (Where XA denotes at least one kind of element selected from thethird group consisting of Sr, Ca and lanthanoide; XB denotes at leastone kind of element selected from the first group consisting of Co andFe; XC denotes at least one kind of element selected from the secondgroup consisting of In, Y, and Sn; XD denotes at least one kind ofelement selected from the fourth group consisting of Nb, Ta, Ti, and Zr;XE denotes at least one kind of element selected from the fifth groupconsisting of Cu, Ni, Zn, Li and Mg; and XF denotes at least one kind ofelement selected from the sixth group consisting of Cr, Ga, and Al. Asfor the range of rbal, when XC contains only In, it fulfills thecondition of 0.4≦rba1≦1.0; when XC contains only Y, it fulfills thecondition of 0.5≦rba1≦1.0; when XC contains only Sn, it fulfills thecondition of 0.2≦rba1≦1.0; and when XC contains two or more elementscomposing the second group, it fulfills the condition of 0.2≦rba1≦1.0.As for the range of rc, when XC contains only Y, it fulfills thecondition of 0.06≦rc≦0.3; when XC contains at least either one of In orSn, it fulfills the condition of 0.02≦rc≦0.3. The range of rd fulfillsthe condition of 0≦rd≦0.2; the range of re, fulfills the condition of0≦re≦0.2; the range of rf, fulfills the condition of 0≦rf≦0.2; the rangeof α, fulfills the condition of 0.9≦α≦1.1. δ is a value determined tofulfill the condition of neutral electric charge.)

[0052] A ceramic composition relating to the first invention has aperovskite structure. A site of the perovskite structure may contain onekind of element or a plural kinds of elements selected from Sr, Ca,lanthanoide elements and so on as well as Ba. These elements correspondto XA in formula 1. As described above, when one or more elements otherthan Ba is made to co-exist in A site, the stability of the perovskitestructure is improved more.

[0053] However, as clear from the description above, in order to obtaina mixed conductor material having a higher oxygen permeation rate, Ba ispreferably contained in a high ratio. A preferable ratio of Ba tomaintain the perovskite structure stable depends on the kind of elementdenoted by XC in formula 1 whether it is In, Y or Sn. The ratio of Ba inA site is expressed by ra in formula 1. When XC is In, the value of rais in the range of 0.4≦ra≦1.0, more preferably 0.6≦ra≦1.0. When XC is Y,the value of ra is in the range of 0.5≦ra≦1.0, more preferably0.6≦ra≦1.0. When XC is Sn, the value of ra is in the range of0.2≦ra≦1.0, more preferably 0.5≦ra≦1.0. When XC is a combination of twoor more kinds among In, Y, or Sn, the value of ra is in the range of0.2≦ra≦1.0, more preferably 0.6≦ra≦1.0. If the value of ra is smallerthan these ranges, in other words, when the ratio of Ba is small,stabilization of the perovskite structure is not sufficient, and adifferent phase such as BaNiO₃ is created.

[0054] B site in the perovskite structure contains at least either oneof Co or Fe, and is required to contain at least one out of In, Y, andSn without fail. As described earlier, In, Y, or Sn can be used alone,or can be used in combination. The ratio of total sum of In, Y, and Snin B site is expressed as rc in formula 1. When XC is Y alone, the valueof rc is in the range of 0.06≦rc≦0.3. When XC is either In or Sn, or acombination of two or more kinds among In, Y, and Sn, the value of rc isin the range of 0.02≦rc≦0.3, more preferably 0.05≦rc≦0.2. If the totalsum of In, Y, and Sn is made large, the stability of the perovskitestructure is improved, but if the total sum is made much larger thanthis range, it turns into problems such as generation of a second phase,lowering of oxygen permeation property, and so on. On the contrary, ifit is made smaller than this range, the stabilization of the perovskitestructure is not sufficient.

[0055] The ceramic composition (mixed conductor material) according tothe first invention may contain Nb, Ta, Ti, Zr, Cu, Ni, Zn, Li, Mg, Cr,Ga, Al, and so on other than these elements. Any of these elementsreplaces B site of the perovskite structure, provided that there is apreferable range for replacement for each element in view of oxygenpermeation rate or stability of the perovskite structure. XD in formula1 is any one of Nb, Ta, Ti, and Zr, or a combination of two or morekinds among these elements. XE in formula 1 is any one of Cu, Ni, Zn,Li, and Mg, or a combination of two or more kinds among these elements.XF is any one of Cr, Ga, and Al, or a combination of two or more kindsamong these elements. The value of rd is preferably in the range of0≦rd≦0.2, the value of re is preferably in the range of 0≦re≦0.2, andthe value of rf is preferably in the range of 0≦rf≦0.2. Increase of theamount of element replacement beyond these ranges causes a problem suchas creation of a different phase, large decrease of oxygen permeationrate, and so on. In addition to the above, in order to obtain higheroxygen permeation rate, it is preferable for the value of“1−rc−rd−re−rf” showing the Co content and Fe content to be 0.7 or more.

[0056] The ratio α of A site to B site is in the range of 0.9≦α≦1.1,more preferably in the range of 0.98≦α≦1.02. It is possible to controldegree of sintering of materials by shifting the ratio α from 1 to somedegree. However, if the ratio of A site and B site is out of this range,it is not favorable because of creation of the second phase. Especiallywhen it contains Y, if the value of α is smaller than 0.9, it tends moreto create a different phase.

[0057] Even if this ceramic composition (oxygen ion mixed conductor)contains a few impurities, there occurs no big deterioration in itscharacteristic feature. However, the allowance is preferably 5% or lessto the total when expressed by mole ratio of the elements, morepreferably 2% or less. If it contains impurities in an amount largerthan this range, it may cause a problem of creating a different phase,lowering of oxygen permeation rate or others. On the other hand, theceramic composition of the first invention (oxide ion mixed conductor)can make a composite with the second phase in a degree of not giving aninfluence to oxygen permeation ability. For instance, when a compositeis made with an amount of about 2 to about 20 mass % of metal such asAg, Ag—Pd, Pt and the like, it is possible to increase an ability ofsintering and material strength.

[0058] As will be described later, the ceramic composition relating tothe first invention can be also used as a porous substrate, a densecontinuous layer, or as a catalyst for promoting oxygen exchangereaction on a membrane surface in a composite material for oxygenseparation or chemical reaction apparatus. When this material is used asa porous substrate, it can match relatively with ease in thermalexpansion with metal members and the like composing an apparatus and aneffect of promoting an oxygen exchange reaction between a gas phase andan oxide ion mixed conductor on a surface of a dense continuous layer.On the other hand, when this material is used as a dense continuouslayer, it becomes possible to produce a composite material havingespecially a high oxygen permeation rate.

[0059] The ceramic composition relating to the first invention isapplicable to a composite material. In such a composite material, aporosity of a porous substrate is required to be 20% to 80%. When theporosity is out of this range, it turns into a problem such asgeneration of high ventilation resistance during oxygen permeation, orbig damage in mechanical characteristics of the supporter. Though apreferable range of the thickness of the porous substrate differsaccording to the structure or operational conditions of apparatus, it istypically 500 μm to 10 mm. If the thickness of the porous substrate isthicker than this range, it may cause a problem of making theventilation resistance large during oxygen permeation. If the thicknessof the porous substrate is thinner than this range, it may cause aproblem of making the mechanical characteristics insufficient. On theother hand, an agreeable thickness of a dense continuous layer is 10 μmto 2 mm. If the thickness of the continuous layer is out of this range,it sometimes causes a problem of increase in the amount of leak gas orlowering of oxygen permeation rate.

[0060] For producing a porous substrate in such a composite material, amethod generally used for producing a ceramic porous body is applicable.What can be cited as one of the method for producing a porous substrateis that oxide containing necessary elements is used as a raw materialand sintered. Another method is that salts, for instance, inorganicsalts such as carbonate, nitrate, sulfate, and the like, organic saltssuch as acetate, oxalate, and the like, halides such as chloride,bromide, iodide and the like, or hydroxide or oxi-halide are used otherthan oxide as a raw material, and mixed in a predetermined ratio, andsintered. A method of dissolving a water-soluble salt among theabove-described salts at a predetermined ratio to evaporate and dry thesolution, a method of drying with a freeze dry method, and a spray drymethod, then to sinter, a co-precipitation method of dissolving awater-soluble salt in water, and thereafter, adding an alkaline solutionsuch as aqueous ammonia to co-precipitate as a hydroxide and to sinter,or a sol-gel method and the like of using metal alkoxide as a rawmaterial, and hydrolyzing it to obtain a gel and to sinter can be used.

[0061] Sintering of a porous substrate is generally conducted in atwo-step of calcinations and main firing (sintering). The calcinationsis generally conducted at the temperature range of 400 to 1000° C. forseveral hours to ten and several hours to produce a calcinated powder.It is also possible to mold the powder after calcination (calcinatedpowder) without any process for successive main sintering, or to mixresin such as polyvinyl alcohol (PVA) into the calcinated powder formolding and main sintering. Though the temperature for main sinteringdepends on composition and the like, it is generally in the range of 700to 1400° C., and preferably in the range of 1000 to 1350° C. Though themain sintering period of time depends on the composition and thetemperature for sintering, it generally requires several hours or more.It is sufficient for the atmosphere of the main sintering to begenerally in the air, but it is also acceptable to conduct sinteringunder a controlled atmosphere if necessary. As a method of molding aporous substrate, similarly to a typical production method of bulkceramics, it is acceptable to pack the calcinated powder or mixed powderin a dice to carry out pressure molding, and also acceptable to useslurry casting, an extrusion method or the like.

[0062] The dense continuous membrane in the ceramic composition relatingto the first invention can be manufactured by a method usually used formanufacturing, for instance, a ceramic membrane. It is also possible tomake a membrane by the so-called thin-film forming method such as PVD orCVD in the vapor deposition method or the like. As a simpler and moreeconomical method, it is preferable to adopt a method of coating aporous substrate with a raw material powder or a calcinated powder in aslurry state and then sintering it.

[0063] As the temperature for sintering of the dense continuousmembrane, it is necessary to create conditions under which a densemembrane can be formed lest gas leakage should occur and lest theporosity of the porous substrate should become much lower during thesintering process. A temperature for main sintering is usually in therange of 700 to 1400° C., and preferably 1000 to 1350° C. For thesintering period of time, it generally needs several hours. Sintering ofthe dense continuous membrane may be conducted after main sintering ofthe porous substrate separately, or it may be conducted simultaneouslywith the main sintering of the supporter. The density of the densecontinuous membrane is preferably 85% or more of the theoretical densitylest gas leakage should occur, more preferably 93% or more.

[0064] With the composite material formed by the above-describedprocess, in order to perform selective permeation and separation ofoxygen from mixed gas containing oxygen, it can be realized by making apotential of oxygen on both side of the composite material differentfrom each other. For instance, in order to separate oxygen from air, itis sufficient to apply pressure on an air side or a raw material side,or to reduce pressure on a take-out side of oxygen. For instance, oxygencan be produced by applying pressure on the air side at 10 to 30 atm,and adjusting the oxygen-permeating side to one atm. It is alsoacceptable to apply 1 to 30 atm of pressure on the air side and toreduce the oxygen-permeating side to about 0.05 atm. Further, in orderto produce oxygen rich air, it is sufficient to apply pressure of 10 to30 atm on the air side, and supply 1 atm of air on the opposite side.The temperature of oxygen-separation work is in the range of 500 to1000° C., preferably in the range of 650 to 950° C.

[0065] Thus, the ceramic composition relating to the first invention andcomposite materials to which the ceramic composition is applied can beapplied to apparatuses and the like for producing pure oxygen or oxygenrich air. It is also applicable in uses other than oxygen separation,especially, a chemical reaction apparatus involving an oxidationreaction. For instance, it is possible to apply it to a reactionapparatus of a partial oxidative reaction of methane for producingsynthetic gas composed of carbon monoxide and hydrogen from methane.Conventionally, a reaction apparatus to obtain synthetic gas by acatalytic reaction using mixed gas of methane and oxygen as a rawmaterial has been used. On the other hand, in a reaction apparatus usingthe ceramic composition (oxide ion mixed conductive ceramics) relatingto the first invention, for instance, it is sufficient to let air (ormixed gas containing oxygen) and methane flow separately, partitioned byan oxide ion mixed conductor, and to arrange a catalyst for syntheticgas production such as Rh or the like on the surface of the oxide ionmixed conductor on the side where methane flows by coating or the like.By heating ceramics at the range of about 500 to about 1000° C., onlyoxygen permeates based on the same principle as oxygen separation, thenreacts with methane on the surface of the ceramics on the methane sideto produce synthetic gas.

[0066] Accordingly, when a chemical reaction apparatus applying theceramic composition relating to the first invention is used, there is noneed to produce oxygen in advance as was required in the case of theprior art and no raw material gas is involved. Therefore, a large effectsuch as synthetic gas can be obtained effectively, a productionapparatus can be simple because the reaction occurs successively, and soon is assured. Further, the ceramic composition relating to the firstinvention can be applied to all chemical reaction apparatus involvingoxidative chemical reaction such as partial oxidation of hydrocarbon toform olefin, partial oxidation of ethane, substitution of aromaticcompounds, and so on other than partial oxidation of methane.

[0067] An experiment of the first invention will be explained next.However, this is only for explaining the first invention by using theexperiment, and the scope of the first invention is not limited to thisexperiment.

[0068] In this experiment, dense sintered samples were prepared, andeach crystal structure and oxygen permeation rate was evaluated. CaCO₃,SrCO₃, BaCO₃, La₂O3, Fe₂O₃, Co₃O₄, In₂O₃, Y₂O₃, SnO₂, Nb₂O₅, Ta₂O₃,TiO₂, ZrO₂, CuO, NiO, ZnO, Li₂CO₃, MgO, Cr₂O₃, Ga₂O₃ and Al₂O₃ were usedas raw materials. After weighing a predetermined amount for each sample,mixing by a ball mill with zirconia balls was conducted for 24 hoursusing isopropyl alcohol as a dispersion medium. Obtained slurry wasdried and crashed into powder, packed into a square pod made of MgO, andcalcinated exposed to air for 12 hours at 850° C. Then, the obtainedcalcinated powder was pulverized, filled into a die of 12 mm φ, formedinto a tablet by uniaxial pressing, and packed further into an ice bagto conduct CIP forming. Then, the obtained molded product was sinteredin a square pod made of MgO at a sintering temperature between 1000° C.and 1300° C. for 5 hours to obtain a sintered sample of about 10 mmφ indiameter.

[0069] The sintered sample was polished to 1 mm in thickness, made toadhere on a top of an Al₂O₃ tube, and the inside of the tube wasdecompressed while the outside was exposed to the air to measure thepartial pressure of oxygen on the decompressed side, and the oxygenpermeation rate was evaluated based on the difference from a partialpressure value in the case of no oxygen permeation through the sinteredsample. The sample temperature was set to 850° C. The oxygen permeationrate is expressed by a permeated volume of oxygen in a standard stateper one minute per unit surface area of the oxide ion mixed conductor,and the unit is ml/min/cm². Presence of gas leakage through the sinteredsample was confirmed by replacing the outside atmosphere into a mixtureof air and helium, using a helium leak detector. As a result, no gasleakage was recognized for the samples within the scope of the presentinvention.

[0070] Compositions of the sintered samples, the result ofidentification of the component phase using a powder X-ray diffractionmethod at a room temperature, and a measured value of the oxygenpermeation rate are shown in Table 1 and Table 2.

[0071] In Table 1 and Table 2, composition of the sample is expressed byconstitutional elements and rate of composition according to theabove-described formula (formula 1).

(Ba_(rba1)XA_(1−rba1))α(XB_(1−rc−rd−re−rf)XC_(rc)XD_(rd)XE_(re)XF_(rf))O_(3−δ)  (formula1)

[0072] In the column of component phase, ∘ indicates that it is a singlephase of cubic perovskite phase, and X indicates that it contains adifferent phase such as BaNiO₃ type hexagonal structure. From Table 1and Table 2, it can be confirmed that the crystal structure of materialswithin the scope of the first invention is a cubic perovskite structurestable even at a room temperature and is high in permeation rate ofoxygen.

Second Invention

[0073] The second invention will be explained next.

[0074] In the second invention, the ceramic composition relating to thefirst invention and composite material to which it is applied can beused. However, the second invention is not limited to those.

[0075] As described above, improvement of oxygen permeation rate(synthetic gas production rate) per unit area requires conducting ofthree processes of a cathodic reaction, diffusion transfer of oxygenion, and anodic reaction in co-ordination with each other.

[0076] In the second invention, the present inventors first paidattention to increase of a reaction field which is generally well-knownas a method of promoting cathodic reaction to make an oxygen molecule inoxygen containing gas into oxygen ion namely increase of surface areaobtained by addition of a porous catalyst layer. By allowing the porouscatalyst layer including mixed conducting oxide to be contiguous to asecond surface of the dense continuous layer, remarkable promotion ofthe cathodic reaction can be achieved. Mixed conductive perovskite oxidehaving high oxygen permeability is suited for material of the porouscatalyst layer. As a result of assiduous search for the porous catalystlayer materials having high oxygen permeability, material composed ofperovskite oxide whose composition is expressed by the compositionformula (formula 2) was found.

(Ln_(1−rg−rba3)XG_(rg)Ba_(rba3))(XH_(rh)XI_(ri)XJ_(rj))O_(3−δ)  (formula2)

[0077] (Where Ln denotes at least one kind of element selected fromlanthanoide; XG denotes at least one kind of element selected from aseventh group consisting of Sr and Ca; XH denotes at least one kind ofelement selected from an eighth group consisting of Co, Fe, Cr, and Ga,in which the sum total of the number of moles of Cr and Ga is 0 to 20%to the sum total of the number of moles of the elements composing theabove-described eighth group; XI denotes at least one kind of elementselected from a ninth group consisting of Nb, Ta, Ti, Zr, In and Y,including at least one kind of element selected from a tenth groupconsisting of Nb, Ta, In and Y; and XJ denotes at least one kind ofelement selected from an eleventh group consisting of Zn, Li and Mg. Asfor the range of rba3, when XI contains only In, it fulfills thecondition of 0.4≦rba3≦1.0, when XI contains only Y, it fulfills thecondition of 0.5≦rba3≦1.0, and when XI contains only In and Y, itfulfills the condition of 0.2≦rba3≦1.0. The range of “rg+rba3” fulfillsthe condition of 0.8≦rg+rba3≦1, the range of rh fulfills the conditionof 0<rh, the range of ri fulfills the condition of 0<ri≦0.5, the rangeof rj fulfills the condition of 0≦rj≦0.2, and the range of “rh+ri+rj”fulfills the condition of 0.98≦rh+ri+rj≦1.02. δ is a value determined tofulfill the condition of neutral electric charge.)

[0078] It is suitable to use perovskite structure oxide having high ionconductivity as a material, as is generally known, in order to increasethe oxygen ion diffusion rate in the dense continuous layer. The presentinventors have searched a material which has high ion conductivity andconformity with porous catalyst layer material and intermediate catalystlayer materials (no exfoliation occurs when sintering a porous layer,and so forth) as concrete materials and found material composed ofperovskite oxide whose composition is expressed by formula 2, namely,material expressed by the same general formula as that of the porouscatalyst layer is suitable, as a result after an assiduous activity.

[0079] On the other hand, concerning a method of promoting the anodicreaction in which hydrocarbon gas such as methane and the like isoxidized, the present inventors have found for the first time that astructure—in which a porous intermediate catalyst layer having mixedconducting oxide is allowed to be contiguous to a dense continuouslayer, not that a conventionally well-known method of a porous reactivecatalyst layer to be contiguous to the dense continuous layer, and theporous reactive catalyst layer is allowed to be contiguous to the densecontinuous layer via the porous intermediate catalyst layer—is extremelyeffective to promote the anodic reaction. As material for the porousintermediate catalyst layer, high oxygen-permeable mixed conductingoxide having high reduction-resistance is suited so as to promote theanodic reaction stably even in a reducing atmosphere due to hydrocarbonor the like. As a result of assiduous search of mixed conductive, highoxygen-permeable perovskite oxide having reduction-resistance, thepresent inventors have found that perovskite oxide having the samecomposition as that of the porous catalyst layer or the dense continuouslayer fulfills these conditions.

[0080] Besides, for the porous intermediate catalyst layer, it is alsoeffective to include catalytic oxide not having mixed conductivity buthaving a combustion catalytic function, namely oxide containing one kindor two kinds or more among Co, Fe, Mn or Pd. The porous intermediatecatalyst layer in the present invention may have both of these mixedconducting oxide and catalytic oxide or only one. For material forporous reaction catalyst layer, considering high temperature operation,as a result of assiduous search for the material not to react withperovskite oxide forming the porous intermediate catalyst layer, buthave conformity with the porous intermediate catalyst layer material (noexfoliation occurs when bonding by calcination, and so forth), thepresent inventors have found that MgO having extremely low in reactivityis suitable for a catalyst support used for a reaction catalyst layer,and as a reaction catalyst, it is suitable to allow one or two or moreactive metal kinds selected from the group consisting of Ni, Co, Ru, Rh,Pt, Pd, Ir, and Re to be supported by a support. It should be noted thatin the case of only porous intermediate catalyst layer containing mixedconducting oxide without a porous reactive catalyst layer, since acomplete oxidation reaction of hydrocarbon is promoted as an anodicreaction, it is not suited to the production of synthetic gas.Therefore, this case is not included in the scope of the presentinvention.

[0081] The relation between what the present inventors intended and theprior art in the second invention is as follows. As for the porouscatalyst layer and dense continuous layer (dense membrane portion) inthe cathode side, there is no big structural difference from the priorart. However, material suited for this portion is disclosed concretelyin the second invention. As for an anode side configuration, there is abig difference between the second invention and the prior art. Thepresent inventors have invented a new method of dividing the anodicreaction into a complete oxidation reaction of hydrocarbon and areforming reaction of the complete oxidation reaction product, andgenerating synthetic gas by a method of allowing these reactions to bepromoted one by one in two contiguous layers.

[0082] By making the anodic reaction into two stages, it becomespossible for the first time to advance a partial oxidative reaction ofhydrocarbon while obtaining stably a high oxygen permeation rate. Thecomplete oxidation reaction of hydrocarbon is conducted through themixed conductive porous intermediate catalyst layer. The mixedconducting oxide is suitable for a catalyst to advance the completeoxidation reaction rapidly. This is because mixed conducting oxide has acharacteristic to advance the anodic reaction to convert oxygen iondiffusing through the dense continuous layer into oxygen atom on thesurface of the dense continuous layer and the oxygen atom oxidativelydecomposes the hydrocarbon molecule adsorbed on the catalyst surfaceimmediately. It is necessary to make the intermediate catalyst layer tobe porous because it makes the complete oxidation reaction rate high byincreasing the reaction surface area 0, and exchange of raw material gassuch as hydrocarbon and the like and water vapor and carbon dioxide as areaction product are performed rapidly. For a reforming reaction(synthetic gas generation reaction) of hydrocarbon and the like withwater vapor and carbon dioxide gas, it is advisable to use one kind ortwo kinds or more of active metal(s) selected from the group consistingof Ni, Co, Ru, Rh, Pt, Pd, Ir, and Re, known as a reforming reactioncatalyst. However, it is necessary to widen reaction surface area so asto increase the reaction rate and to let a support hold the porouscatalyst to make a porous reactive catalyst layer so that exchange ofvarious gas of raw material gas such as hydrocarbon and the like, watervapor, carbon dioxide, synthetic gas and so on. The present inventorshave not only invented the above-described new structure for the anodicreaction but also concretely disclosed material suited for this portion.

[0083]FIG. 1 is a sectional view showing a structure of compositematerial of catalyst and ceramics relating to a first embodiment of thesecond invention. In the first embodiment, a porous catalyst layer 2 iscontiguous to a second surface 1 a of a dense continuous layer 1. On theother hand, a porous intermediate catalyst layer 3 is contiguous to afirst surface 1 b of the dense continuous layer 1. Further, a porousreactive catalyst layer 4 is formed on a porous intermediate catalystlayer 3.

[0084] In the second invention, the multi-layered structure consistingof the porous catalyst layer, the dense continuous layer, the porousintermediate catalyst layer and the porous reactive catalyst layer maybe formed on the porous substrate, as a covering layer. With thisstructure, since mechanical strength can be enhanced, resistance isincreased in the case that the pressure on the cathode side and thepressure of raw material gas on the anode side differs from each other,and there is a difference in total pressure via the dense continuouslayer. Any material can be accepted for the material of a poroussubstrate as long as it has mechanical strength and conformity withaforementioned multi-layered structure, for instance, even mixedconducting oxide can be accepted. Further, the porous catalyst layer maybe made thick so as to also have functions as a porous substrate.Further, the porous substrate material can be formed from the ceramiccomposition relating to the first invention.

[0085]FIG. 2 is a sectional view showing a structure of a compositematerial of catalyst and ceramics relating to a second embodiment of thesecond invention. In the second embodiment, the multi-layered structureis formed from the porous catalyst layer 2, the dense continuous layer1, the porous intermediate catalyst layer 3 and the porous reactivecatalyst layer 4, and this multi-layered structure is formed on theporous substrate 5, as a covering layer. To the porous substrate 5, forinstance, the porous catalyst layer 2 is contiguous.

[0086] In the second invention, the thickness of the dense continuouslayer is preferably 1 μm to 2 mm, more preferably 10 μm to 1.5 mm, muchmore preferably 30 μm to 1 mm. When the dense continuous layer is toothick, it becomes impossible to make the oxygen permeation rate large.On the contrary, when the dense continuous layer is too thin, mechanicalreliability becomes poor. Accordingly, there is an appropriate range inthe thickness of the dense continuous layer. Porosity of theaforementioned porous intermediate catalyst layer and porous catalystlayer is preferably 20% to 80%, more preferably 30% to 60%. If theporosity of the porous intermediate catalyst layer and the porouscatalyst layer is too small, transfer of raw material gas and reactionproduct is blocked to hinder increase of oxygen permeation rate(synthetic gas production rate). On the other hand, if the porosity istoo large, mechanical reliability becomes poor. Accordingly, theporosity has a suitable range as described before.

[0087] As material for the porous reactive catalyst layer material, asdescribed above, it is desirable in view of activity and conformity withthe porous intermediate catalyst layer to use a support having MgO as amain component and supporting one kind or two kinds or more of activemetal selected from the group consisting of Ni, Co, Ru, Rh, Pt, Pd, Ir,and Re, which are active to hydrocarbon in reforming of water vapor andcarbon dioxide. It should be noted that the porous reactive catalystlayer performs not only reforming of hydrocarbon but also an importantrole of avoiding formation of a hot spot which leads to materialdeterioration by transferring heat generated on the porous intermediatecatalyst layer in which a complete oxidation reaction of hydrocarbon andthe like occurs to the porous reactive catalyst layer (creation of anendothermic reaction).

[0088] Examples of production method for the porous catalyst layer, thedense continuous layer, the porous intermediate catalyst layer, and thereactive catalyst layer will be explained next.

[0089] For the raw materials for ceramics to form the porous catalystlayer, the dense continuous layer or the porous intermediate catalystlayer, metal salt such as metallic oxide, metal carbonate, and the likeis used, and the raw materials are prepared by mixing and sintering theabove-described materials. It is also acceptable for preparation ofpowdered materials to use co-precipitation method, metal alkoxide method(sol-gel method) or other methods for preparation equivalent to thesemethods. The mixed raw material powder is calcinated at a predeterminedtemperature. For the materials for forming the dense continuous layer,samples after calcinations are finely pulverized, mixed uniformly, andthereafter, molded. For the molding, any suitable ceramic productiontechnology such as CIP (cold isostatical press), HIP (hot isostaticalpress), mold press, injection molding method, slip casting method,extrusion molding method, and so on can be applied. Molded sample issintered at a high temperature.

[0090] For the porous catalyst layer and the porous intermediatecatalyst layer material, the raw materials are prepared, mixed,calcinated and pulverized and sintered at high temperatures withoutmolding, which is different from the production process for the densecontinuous layer. If the raw materials are uniformly mixed, it ispossible to sinter directly here, omitting the calcination process atthe middle. It is necessary to conduct sintering at a temperature forsintering at which a perovskite structure displaying mixed conductivitycan be created. The sintered sample is finely pulverized by a suitablemethod such as ball mills. The diameter of the pulverized powder ispreferably 10 μm or less for the reason described later.

[0091] The porous catalyst layer and the porous intermediate catalystlayer are formed by mixing the pulverized powder and an organic solventor the like to make a slurry which is then used to coat the densecontinuous layer surface. The dense continuous layer is sintered(firing) after drying. Generally, the smaller and more uniform theparticle size of the powder to be coated, or the thinner the coatedmembrane, the more uniformly it can be coated on the surface ofmembrane. More concretely, it is desirable to adjust the particle sizeof the powder to be 10 μm or less. For formation of the porousintermediate catalyst layer, a CVD (chemical vapor deposition) method,an electrophoresis method, a sol-gel method, or any other suitablemethod can be used other than the above-described method. The porouslayer formed by these methods are sintered in a manner that the porouslayer and the dense continuous layer are joined firmly in order tosecure the continuity in mixed conductivity at the interface with thedense continuous layer. A suitable temperature for firing at which firmbonding is obtainable is determined to be below the melting point of thematerial lower in melting point of either the porous layer or the densecontinuous layer. Among materials described in the embodiments or thelike to be described later, firm bonding can be obtained at thesintering temperature of 950° C. or more.

[0092] As material for the catalyst forming the reactive catalyst layer,it is desirable to use a support having magnesia as a main componentsuuporting one kind or two kinds or more of active metal selected fromthe group consisting of Ni, Co, Ru, Rh, Pt, Pd, Ir, and Re. As a methodof preparing a catalyst, any method of an impregnation holding method,an equilibrium adsorption method, a co-precipitation method or the likecan be selected. A desirable amount of holding active metal is 3 to 30mol % to the support in the case of Ni or Co, 0.1 to 10 wt % in the caseof Ru, 0.01 to 3 wt % in the case of Rh, Pt, Pd, Ir and Re. Besides, itis possible to combine these metals. In order to disperse the activemetal widely, Ni or Co may dissolve in magnesia. In this case, theco-precipitation method or a ceramic method may be used.

[0093] The reactive catalyst layer is formed by adding a minute amountof fine powder of the porous intermediate catalyst layer material to aminutely pulverized powder of a prepared catalyst to mix thoroughly.This mixture powder is then put into and mixed with an organic solventor the like to make a slurry which is used to coat on the porousintermediate catalyst layer, which is sintered (fired) after dried toform the reactive catalyst layer. Generally, the smaller and moreuniform the particle size of the powder to be coated, or the thinner thecoated membrane, the more uniformly it can be coated on the surface ofthe membrane. More concretely, it is desirable to adjust the particlesize of the powder to 10 μm or less. It is desirable to select thetemperature for sintering to be a suitable temperature at which firmjoining is obtainable, in the temperature range at least 50° C. higherthan an actual operation temperature of the membrane reactor, but lowerthan the melting point of the composite material of ceramics, and sinterin the air. With the materials in the experiments described later, firmjoining can be obtained at the sintering temperature of 950° C. orhigher.

[0094] Amount by weight of the catalyst per unit membrane area ispreferably in the range of 20 to 50 mg/cm². Depending on an operationcondition of the membrane reactor, there is also a method of particlesize adjustment of the reactive catalyst and arranging without sinteringon the porous intermediate layer. Further, there is also a method ofcombining the slurry coating and particle size adjusted catalystarrangement.

[0095] Experiments of the second invention will be explained next.However, this is only for explaining the second invention by using theexperiment, and the scope of the second invention is not limited to thisexperiment.

Experiment 1 of the Second Invention

[0096] Commercially available powder of SrCO₃, Fe₂O₃, and Nb₂O₅ ofpurity 99% or more was weighed at a mole ratio of Sr:Fe:Nb=1:0.9:0.1,and wet mixing for 2 hours was conducted using a planetary ball mill.The obtained raw material powder was put into an alumina crucible andsintered for 5 hours at 1350° C. in the air to obtain a composite oxide.The measurement result of this composite oxide by powder X-raydiffraction at a room temperature showed that the main component was acubic perovskite structure, and was confirmed to be composite oxidewhose composition was expressed by SrFe_(0.9)Nb_(0.1)O_(3−δ). Thiscomposite oxide was crushed into powder having the particle size of 10μm or less by an automatic mortar to obtain the porous intermediatecatalyst layer material.

[0097] Next, commercially available powder of BaCO₃, SrCO₃, CoO, andFe₂O₃ of purity 99% or more was weighed at a mole ratio ofBa:Sr:Co:Fe=0.5:0.5:0.8:0.2 and wet mixing for 2 hours was conductedusing a planetary ball mill. The obtained raw material powder was putinto an alumina crucible and calcinated for 20 hours at 950° C. in theair to obtain composite oxide. After the composite oxide was wet crushedinto powder for 2 hours by a planetary ball mill and 3 g of this powderwas molded into a disk at 25 MPa with a metal mold of 20 mm in diameter.After putting this molded body into an airtight bag, and the bag wasdeaerated into vacuum, this molded body was given CIP for 15 min, whilepressurizing at 200 MPa, and sintered for 5 hours at 1130° C. in the airto obtain a dense sintered body having a relative density of 95% ormore. The measurement result of this sintered body by powder X-raydiffraction at a room temperature showed that the main component was acubic perovskite structure, and was confirmed to be composite oxidewhose composition was expressed byBa_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3−δ). Both faces of the sintered bodywere ground and polished to be a disk of 12 mm in diameter, 0.7 mm inthickness, and used as a dense continuous layer.

[0098] Then, a sintered body obtained by the same method and expressedby a composition of Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3−δ) waspulverized into a powder of 10 μm or less in particle size to obtain theporous catalyst layer material. This material was suspended in anorganic solvent to be a slurry state, which was coated on a secondsurface of the disk dense continuous layer. Further, the porousintermediate layer material described above was made in a slurry statesimilarly, which was coated on a first surface of the dense continuouslayer. Then, after the dense continuous layer coated with two kinds ofslurry was dried for 5 min at 120° C., the porous catalyst layer and theporous intermediate catalyst layer joined firmly with the densecontinuous layer was obtained by sintering for 5 hours at 1050° C. inthe air. At this time, the thickness of the porous catalyst layer andthe thickness of the porous intermediate catalyst layer were 0.3 mm and0.2 mm respectively. Next, 5 mg of fine powder of the porousintermediate catalyst layer material was added to 28 mg of powder(particle size of 10 μm or less) of hydrocarbon-reforming catalyst, inwhich Ni was dissolved in magnesia at a ratio of 10 mol % in regard toMg and mixed thoroughly, which was suspended in an organic solvent, andslurry coated on the porous intermediate catalyst layer. This was driedat 120° C. for 5 minutes, and thereafter sintered at 1050° C. for 5hours in the air, so that a catalyzed composite material of ceramics wasobtained by joining the porous intermediate catalyst layer with thehydrocarbon-reforming catalyst layer (porous reactive catalyst layer).This composite material of ceramics was used for experiment of oxygenpermeation (synthetic gas production).

[0099] The experiment was conducted by sandwiching the compositematerial of catalyst and ceramics with two pieces of mullite tubes viasilver rings under a pressure of 10 atm at 900° C. while airtight of thecathode side and the anode side was kept. As for the raw material gas,air was supplied on the cathode side at a rate of 200 cc/min and methanewas supplied on the anode side at a rate of 40 cc/min. An output gas onthe anode side was measured with a gas chromatograph and an oxygenpermeation rate from the air side to methane side in a stable stateowing to element balance was calculated.

[0100] As a result of the experiment, the oxygen permeation rate was 21cc/min/cm². At this time, the methane reaction conversion ratio, COselection ratio (CO ratio in CO and CO₂), H₂/CO ratio were 58%, 80%, and1.8, respectively. During the experiment, no crack and the like occurredin the dense continuous layer of composite material of catalyst andceramics relating to experiment 1 in the second invention, and anysymptom of time-varying destruction was not recognized at all. Thecomposite material of catalyst and ceramics relating to this experimentshowed a stable oxygen permeation (synthetic gas generation) rateexcepting a period just after starting of experiment and any symptom ofdeterioration was not recognized.

Experiment 2 of the Second Invention

[0101] A suspension liquid was slurry coated on the porous intermediatecatalyst layer of a disk-shaped composite body consisting of the porouscatalyst layer, the dense continuous layer, and the porous intermediatecatalyst layer obtained by the same method as that described in theexperiment 1. The suspension liquid was prepared in a manner that 5 mgof fine powder of the porous intermediate catalyst layer material wasadded to 30 mg of power (particle size of 10 μm or less)hydrocarbon-reforming catalyst in which 5 mol % of Ni was impregnatedand held in magnesia. This was mixed thoroughly and was suspended in anorganic solvent. After a slurry coated composite body was dried at 120°C. for 5 min, a hydrocarbon reforming catalyst layer (porous reactivecatalyst layer) was joined to the porous intermediate catalyst layer bysintering at 1050° C. for 5 hours in the air and a composite material ofcatalyst and ceramics was obtained.

[0102] An oxygen permeation experiment was conducted in a similar mannerto that in experiment 1 except arranging, on the porous reactivecatalyst layer of the composite material, 900 mg ofhydrocarbon-reforming catalyst in which 2 wt % of Ru was impregnated andheld into magnesia whose particle size was adjusted to 20/40 mesh andexcept the pressure is 1 atm.

[0103] The result of calculating the oxygen permeation rate in a stablestate was 25 cc/min/cm². At this time, the methane reaction conversionrate, CO selection ratio (CO ratio in CO and CO₂), and H₂/CO ratio were83%, 86% and 1.9 respectively. During the experiment, no crack and thelike occurred in the dense continuous layer of composite material ofcatalyst and ceramics relating to experiment 2 in the second invention,and any symptom of time-varying destruction was not recognized at all.The composite material of catalyst and ceramics relating to the presentexperiment showed a stable oxygen permeation (synthetic gas generation)rate excepting a period just after starting of experiment and anysymptom of deterioration was not recognized.

Experiment 3 of the Second Invention

[0104] Using the same manner as described in experiment 1, a compositematerial of catalyst and ceramics shown in Table 3 was manufactured andthe oxygen permeation (synthetic gas production) characteristic wasevaluated in the same method.

[0105] As a result, the oxygen permeation rate of 20 cc/min/cm₂ or morefor all was obtained. As in the result of experiment 1, it showed astable oxygen permeation (synthetic gas generation) rate and no symptomof deterioration and time-varying destruction was recognized at all.

Comparison 1 of the Second Invention

[0106] Using the similar manner to the method described in experiment 1,a composite material of catalyst and ceramics consisting of a porouscatalyst layer and a dense continuous layer was obtained. Then, 900 mgof hydrocarbon-reforming catalyst in which 2 wt % of Ru was impregnatedand held into magnesia whose particle size was adjusted to 20/40 meshwas arranged on the dense continuous layer to be used for an oxygenpermeation experiment. The experiment was conducted in the same manneras shown in experiment 1 and the oxygen permeation rate in a stablestate was calculated.

[0107] As a result, the oxygen permeation rate was 18 cc/min/cm². Atthis time, the methane reaction conversion rate, CO selection ratio (COratio in CO and CO₂), and H₂/CO ratio were 76%, 96% and 2.0respectively.

Comparison 2 of the Second Invention

[0108] In a similar manner to the method described in experiment 1except using a composite oxide expressed byBa_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3−δ) as a intermediate porouscatalyst layer material, a composite material of catalyst and ceramicsconsisting of the porous catalyst layer, the dense continuous layer, andthe intermediate porous catalyst layer is obtained. Then, 900 mg ofhydrocarbon-reforming catalyst in which 2 wt % of Ru was impregnated andheld into magnesia whose particle size was adjusted to 20/40 mesh wasarranged on the intermediate porous catalyst layer to be used for anoxygen permeation experiment.

[0109] The experiment was conducted in the same manner as in theexperiment 1, and an oxygen permeation rate of about 18 cc/min/cm₂ wasobtained several hours after starting of the experiment. However, theoxygen permeation rate decreased while time elapsed, and a stable oxygenpermeation rate could not be obtained.

Comparison 3 of the Second Invention

[0110] A suspension was slurry coated on a porous intermediate catalystlayer made of a disk-like composite material consisting of the porouscatalyst layer, the dense continuous layer, and the porous intermediatecatalyst layer obtained by a similar manner to the method described inexperiment 1. The suspension is prepared by suspending, into an organicsolvent, 30 mg of powder having a particle size of 10 μm or less of ahydrocarbon-reforming catalyst making an alumina (α type) support beingimpregnated and support 2 wt % of Ru. Then, after drying a compositebody slurry-coated with the suspension for 5 minutes at 120° C., ahydrocarbon-reforming catalyst layer joined to a porous intermediatecatalyst layer was obtained by sintering for 5 hours at 1050° C. in theair to be used for an oxygen permeation experiment. The experiment wasconducted in a similar manner to the method described in experiment 1except that the pressure applied was 10 atm.

[0111] As a result, an oxygen permeation rate of about 20 cc/min/cm² wasobtained several hours after starting of the experiment. However, theoxygen permeation rate decreased while time elapsed, and a stable oxygenpermeation rate could not be obtained.

Third Invention

[0112] The third invention will be explained next.

[0113] In the third invention, the ceramic composition relating to thefirst invention and the composite material applying the same can be alsoused in a similar manner as in the second invention, but the thirdinvention is not limited to this, either.

[0114] The present inventors first studied concrete selection of denseceramic membrane material, methane-reforming catalyst material and amost suitable combination thereof, with an intention to apply a mixedconducting oxide material low in reduction-resistance but high in oxygenpermeation rate, which was conventionally said to be difficult to usefor a partition membrane for a synthetic gas production, to a denseceramic membrane in composite material of a catalyst for a partitionmembrane and ceramics. As a result, it was found it effective to combineperovskite structure mixed conducting oxide having a specificcomposition range of Nb and/or Ta being added to B site, as a denseceramic membrane material, with a Ni-containing catalyst being supportedon a support having a main component of magnesia, as methane-reformingcatalyst material. Speaking more concretely, the present inventors founda material suitable as a partition membrane material for producingsynthetic gas is composite material of catalyst and ceramics with aspecific feature of having a structure that a catalyst portioncontaining a Ni-containing catalyst, a main component of a catalystsupport being magnesia, is put to be contiguous to a first surface of adense ceramic membrane consisting of oxide ion-electron mixed conductingoxide having a perovskite structure, the dense ceramic membrane beingexpressed by the composition of the formula (formula 2).

(Ln_(1−rg−rba3)XG_(rg)Ba_(rba3))(XH_(rh)XI_(ri)XJ_(rj))O_(3−δ)  (formula2)

[0115] (Where Ln denotes at least one kind of element selected fromlanthanoide; XG denotes at least one kind of element selected from theseventh group consisting of Sr and Ca; XH denotes at least one kind ofelement selected from the eighth group consisting of Co, Fe, Cr, and Ga,in which the sum total of the numbers of moles of Gr and Ga is 0 to 20%to the sum total of the numbers of moles of the elements composing theabove-described eighth group; XI denotes at least one kind of elementselected from the ninth group consisting of Nb, Ta, Ti, Zr, In and Y,including at least one kind of element selected from the tenth groupconsisting of Nb, Ta, In and Y; and XJ denotes at least one kind ofelement selected from the eleventh group consisting of Zn, Li and Mg. Asfor the range of rba3, when XI contains only In, it fulfills thecondition of 0.4≦rba3≦1.0, when XI contains only Y, it fulfills thecondition of 0.5≦rba3≦1.0, and when XI contains only In and Y, itfulfills the condition of 0.2≦rba3≦1.0. The range of “rg+rba3” fulfillsthe condition of 0.8≦rg+rba3≦1, the range of rh fulfills the conditionof 0<rh, the range of ri fulfills the condition of 0<ri≦0.5, the rangeof rj fulfills the condition of 0≦rj≦0.2, and the range of “rh+ri+rj”fulfills 0.98≦rh +ri+rj≦1.02. δ is a value determined to fulfill thecondition of neutral electric charge.)

[0116]FIG. 3 is a sectional view showing a structure of the compositematerial of catalyst and ceramics relating to a first embodiment of thethird invention. In the first embodiment, a porous layer 12 as acatalyst portion is contiguous to a first surface 11 a of a denseceramic membrane 11.

[0117] The present inventors confirmed by experiment that the denseceramic membrane made of the above-described composite material couldmaintain high oxygen permeability without causing crack or split at thetime of preparation and without being deteriorated, destructed due toreductive expansion or the like, and could produce synthetic gas stablyfor a long period of time. For the reason why the above-describedproduction can be realized by using the composite material of catalystand ceramics relating to the third invention is thought to be asfollows.

[0118] On the methane-containing gas side surface of the dense ceramicmembrane being mixed conducting oxide, oxygen ion diffusedly permeatingthrough the membrane is converted into oxygen atom or oxygen molecule,to react with methane (and hydrocarbon) component in the gas containingraw material methane and produce CO₂ and H₂O by a complete oxidationreaction as shown in chemical formula (formula 3).

CH₄+40 (or 2O₂)→CO₂+2H₂O  (formula 3)

[0119] A thermodynamic oxygen partial pressure in a methane-containinggas atmosphere is determined by chemical equilibrium among CO, CO₂, H₂,H₂O, CH₄ and O₂, the larger the ratio of CO₂ and H₂O, the higher thepartial pressure becomes, and on the contrary, the larger the ratio ofCO, H₂, and CH₄ the lower the partial pressure becomes. For instance,when the ratio of CO/CO₂ and the ratio of H₂/H₂O are about 0.01 or lessat 900° C., the partial pressure of oxygen becomes about 10⁻¹⁰ to about10⁻¹² atm (about 1.013×10⁻⁵ to about 1.013×10⁻⁷ Pa) or more. However,when an ordinary methane-reforming catalyst exists, reactions expressedby the chemical formulas mentioned below (formula 4 and formula 5)immediately progress to produce CO and H₂, which makes the partialpressure of oxygen extremely low. In the case where the ordinarymethane-reforming catalyst is contiguous to a dense ceramic membrane,since a reforming reaction progresses also in the vicinity of aninterface between the dense ceramic membrane and methane-reformingcatalyst to make the partial pressure of oxygen extremely low, when lowreduction-resistant mixed conducting oxide is made a dense ceramicmembrane, deterioration and destruction occur by reduction. The presentinventors have experienced these deterioration and destruction manytimes by experiment.

CH₄+H₂O→CO+3H₂  (formula 4)

CH₄+CO₂→2CO+2H₂  (formula 5)

[0120] On the other hand, a Ni-containing catalyst being an essentialconstituent of composite material of catalyst and ceramics relating tothe third invention displays a peculiar function. The Ni-containingcatalyst functions as a methane-reforming catalyst only when Ni is in ametallic state, and does not display a reforming catalytic function whenNi is oxide. On the contrary, though catalytic activity of theNi-containing catalyst is inferior to a mixed conducting oxide, itserves as an oxidation reaction catalyst. A condition that metal Ni isoxidized into oxide is determined by thermodynamics. For instance, at900° C., under an partial pressure of oxygen of about 10⁻¹⁰ to about10⁻¹² atm (about 1.013×10⁻⁵ to about 1.013×10⁻⁷ Pa) or more, oxidebecomes stable. Accordingly, when high oxygen-permeable mixed conductingoxide is made as a dense ceramic membrane, and the Ni-containingcatalyst is made contiguous to this dense ceramic membrane, a partialpressure of oxygen in the vicinity of the interface between the denseceramic membrane and the Ni-containing catalyst is kept as high as tooxidize the Ni-containing catalyst but very little CO or H₂ is producedin the vicinity thereof.

[0121] On the other hand, in the vicinity of a territory where theNi-containing catalyst is exposed to raw material methane-containinggas, the partial pressure of oxygen becomes extremely low due to highCH₄ ratio in the gas, for instance at 900° C., it is far below of 10⁻¹²atm (about 1.013×10⁻⁷ Pa). Under such a circumstance, since Ni in aNi-containing catalyst becomes a metallic state to serve as amethane-reforming catalyst, the reforming reactions expressed by theformula 4 and formula 5 progress to produce synthetic gas as a result.That is, a partial pressure of oxygen is relatively high on the denseceramic membrane side in Ni-containing catalyst portion so that thereforming reaction is restrained, whereas on the raw materialmethane-containing gas side in the Ni-containing catalyst portion, apartial pressure of oxygen is extremely low so that the reformingreaction progresses. The complete oxidation reaction expressed by theformula 5 is an exothermic reaction while the reforming reactionsexpressed by the formulas 4 and 5 are endothermic reactions. In thisendothermic reaction, most of heat of firing reaction generated in thevicinity of the interface between the dense ceramic membrane and theNi-containing catalyst (where a complete oxidation reaction occurs) areabsorbed on the raw material methane-containing gas side of theNi-containing catalyst portion via a reforming reaction. In other words,the Ni-containing catalyst portion also has a function to let the heatgo into the methane-containing gas side so as to restrain excessivetemperature increase of the dense ceramic membrane leading todeterioration of material. In order to transfer the heat efficiently,the Ni-containing catalyst portion and the dense ceramic membrane mustbe contiguous to each other. In order to transfer the gas involved inthe complete oxidative reaction and reforming reaction efficiently, thecatalyst portion needs to be porous. It should be noted that a metalcatalyst other than Ni which becomes oxide or metal at a partialpressure of oxygen having a similar value to that of Ni as a border areCo and Fe. However, these metals are unfavorable as a main active metalin the catalyst portion because of lowness in activity for a reformingcatalyst. In the composite material of catalyst and ceramics relating tothe third invention, it doesn't matter if it contains Co and Fe in theNi-containing catalyst portion, but the main component should be alwaysNi.

[0122] As described previously, when the Ni-containing catalyst portionis made contiguous to the dense ceramic membrane, a partial pressure ofoxygen near the interface between the dense ceramic membrane and thecatalyst is kept moderately high. Therefore, in this case,reduction-resistance of mixed conducting oxide used for a dense ceramicmembrane needs not to be so high compared with the case of making anordinary methane reforming catalyst contiguous, and even with materialhaving a medium level of reduction-resistance, there occurs neitherdeterioration nor destruction. Oxygen ion-electron mixed conductingoxide, which is an essential constituent of the composite material ofcatalyst and ceramics relating to the third invention, whose compositionis expressed by formula 2, and which has a perovskite structure, doesnot cause deterioration and destruction due to reduction even underconditions for producing synthetic gas when at least Ni-containingcatalyst portion is contiguous to the oxygen ion-electron mixedconducting oxide. Further, when a partial pressure of oxygen of rawmaterial air-containing gas or oxygen-containing gas on the cathode sideis high, this material does not lower oxygen permeation rate or does notdestroy due to deterioration of the cathode side surface, even it isexposed to high-pressure air.

[0123] On the contrary, when material to be easily reduced such as(Ba_(1−a)Sr_(a)) (Co_(x)Fe_(y))O_(3−δ) is used for a dense ceramicmembrane, even when a Ni-containing catalyst portion is made contiguousthereto, a production rate of synthetic gas gradually decreases andfinally the membrane would be broken. The reason of relatively highreduction-resistance of the material expressed by formula 2 is thoughtthat Nb, Ta, In, and Y contained in B site have a function to stabilizea perovskite structure intensively, and at the same time, Nb and Tathemselves have a strong affinity with oxygen ion, and Fe in B site hasa similar effect, though the effect is smaller than those of Nb and Ta.In addition to the above, since this material has a characteristic ofhigh oxygen permeability, a sufficient oxygen permeation rate, namelyproduction rate of synthetic gas, can be obtained even with a thickmembrane of 0.5 mm to 2 mm in thickness.

[0124] When the oxygen permeability of this material is desired to beespecially high, it is preferable to adjust the value of rba to be 1.0in formula 2.

[0125] When the composite material of catalyst and ceramics relating tothe third invention is used as a self-supporting membrane, the thicknessof the dense ceramic membrane is set to be in the range of 0.5 mm to 2mm, more preferably in the range of 0.7 mm to 1.3 mm. If it is less than0.5 mm in thickness, it is difficult to be a self-supporting membrane inview of mechanical strength. When the thickness exceeds 2 mm, it isundesirable because oxygen permeation rate, or production rate ofsynthetic gas is decreased. Further, in the composite material ofcatalyst and ceramics relating to the third invention, when thethickness of the dense ceramic membrane is less than 0.5 mm anddifficult to be a self-supporting membrane, or when mechanical strengthis intended to be reinforced as a partition membrane even the thicknessis 0.5 mm or more, it is acceptable to take a thin membrane structurecovered on a porous substrate.

[0126]FIG. 4 is a sectional view showing a composite material structureof catalyst and ceramics relating to a second embodiment of the thirdinvention. In the second embodiment, a multi-layered structure is formedof a dense ceramic membrane 11 and a porous layer 12, and themulti-layered structure is formed as a covering layer on a poroussubstrate 13. To the porous substrate 13, for instance, the denseceramic membrane 11 is contiguous.

[0127] In the event, as a material for the porous substrate, oxygenion-electron mixed conducting oxide, of which composition is expressedby formula 2 and which has a perovskite structure can be used, oranother mixed conducting oxide material such as a ceramic compositionrelating to the first invention can be used. The former oxygenion-electron mixed conducting oxide is also used for, for instance,material for the dense ceramic membrane in the third invention. Theseporous substrate materials have a merit of being able to select materialso that the thermal expansion coefficient is the same as or similar tothat of a covering layer of the composite material of catalyst andceramics relating to the third invention. As a porous substratematerial, heat-resistant material different in thermal expansioncoefficient, for instance, general ceramic material such asheat-resistant metal material, stabilized zirconia and the like can beused. However, in such a case, thermal expansion coefficient of theporous substrate in the thickness direction is changed in sequence bylaminating layers different in thermal expansion coefficient, and thethermal expansion coefficient of a layer joined to a covering layer ofcomposite material of catalyst and ceramics relating to the thirdinvention finally needs to be the same as or similar to the thermalexpansion coefficient of the covering layer of the composite material ofcatalyst and ceramics relating to the third invention.

[0128] In the composite material of catalyst and ceramics relating tothe third invention, a main component of a catalyst support used forNi-containing catalyst portion is magnesia. This is because, under theconditions of producing synthetic gas or in the air, magnesia has aspecific property that it scarcely performs a solid-phase reaction witha mixed conductive material of the dense ceramic membrane or does notperform a solid-phase reaction at all. The present inventors confirmedthis fact by mixing fully pulverized magnesia powder and powder of denseceramic membrane material, by heat-processing it in the air or in amixed gas of CO₂ and H₂O for a long time at high temperatures, and byinvestigating the crystal structure of the heat-processed powder by aX-ray diffraction method after cooling it to a room temperature.

[0129] Since catalyst supports except this, for instance, an aluminasupport performs a solid-phase reaction with mixed conductive material,an oxygen permeation rate or a production rate of synthetic gas may belowered, or the dense ceramic membrane may cause destruction. On theother hand, when a Ni-containing catalyst having magnesia as a maincomponent of the catalyst support is used, such a problem does not ariseeven it is placed contiguous to the dense ceramic membrane.

[0130] As explained above in detail, basic structural features of thecomposite material of catalyst and ceramics of the third inventionconsists of the following four points.

[0131] (a) Perovskite structure mixed conducting oxide in the specificcomposition range having medium reduction resistance and highoxygen-permeability is used as dense ceramic membrane material.

[0132] (b) A catalyst support containing magnesia which does not reactin a solid-phase reaction with the dense ceramic membrane material,preferably having magnesia as a main component is used.

[0133] (c) Ni, as a main component, which becomes oxide under arelatively high partial pressure of oxygen so as not to cause a methanereforming reaction, and becomes metal under a low partial pressure ofoxygen to cause a methane reforming reaction is supported by theaforementioned catalyst support to be a catalyst portion.

[0134] (d) The aforementioned catalyst portion is made contiguous to thedense ceramic membrane. As a result, the partial pressure of oxygen inthe vicinity of the interface between the catalyst portion and theceramic membrane is appropriately increased so that reductivedestruction of the dense ceramic membrane is prevented. A completeoxidative reaction of methane by a permeated oxygen component is made toprogress, and then a reforming reaction of methane is made to progresson a raw material methane-containing gas side of the catalyst portion sothat synthetic gas is produced.

[0135] In the third invention, it is a necessary requirement that theNi-containing catalyst portion is contiguous to the dense ceramicmembrane. If they are apart from each other, a partial pressure ofoxygen in the vicinity of a surface on a raw material methane-containinggas side of the dense ceramic membrane becomes excessively high to makean oxygen permeation rate or a production rate of synthetic gas becomesextremely low. Further, the heat of combustion of the complete oxidativereaction caused on the surface of raw material methane-containing gasside becomes hard to transfer so that it might cause deterioration ordestruction of the membrane due to excessive increase of membranetemperature. Furthermore, it is unfavorable that temperature of thecatalyst portion is lowered to cause restraint of a reforming reaction,and increase of the ratio of CO₂ and H₂O in the synthetic gas.

[0136] In order to make the distance between the Ni-containing catalystportion and the dense ceramic membrane small, and cause a reformingreaction efficiently, it is preferable to make the Ni-containingcatalyst portion 10 μm or less in average pore diameter, and 0.01 mm to1 mm in thickness. And more preferably, it is effective to adopt amethod of preparing a porous layer structure having a thickness of 0.1mm to 0.5 mm to stack on the dense ceramic membrane to join the bothfirmly.

[0137] According to circumstances, it is effective to make a reformingcatalyst portion adjusted to 0.5 mm or more in particle size(hereinafter referred to as a particle size adjusted reforming catalystportion) contiguous to a Ni-containing catalyst portion having theaforementioned porous layer structure (hereinafter referred to as porousNi-containing catalyst layer). Existence of the particle size adjustedreforming catalyst portion depends on a pressure of raw materialmethane-containing gas when synthetic gas is produced using compositematerial of catalyst and ceramics relating to the third invention as thepartition membrane. When a pressure of the raw materialmethane-containing gas is 0.3 MPa or more, preferably 0.5 MPa or more,since a reforming reaction progresses rapidly even with a relativelysmall amount of catalyst, the particle size adjusted reforming catalystportion is not necessarily required. However, since a particle sizeadjusted reforming catalyst portion in which particle size is adjustedto 0.5 mm or more hardly serves as resistance to gas flow, even when rawmaterial methane-containing gas has a high pressure of 0.3 MPa or more,it is still usable though economically unfavorable. On the other hand,when a pressure of raw material methane-containing gas is 0.5 MPa orless, a reforming reaction may not progress sufficiently with a porousNi-containing catalyst layer only, because the reforming reaction rateis relatively low. In such a case, the reforming reaction can becompleted by making a particle size adjusted reforming catalyst portioncontiguous to the Ni-containing catalyst portion. As a catalyst and acatalyst support of the particle size adjusted reforming catalystportion, any material can be adopted so far as that being active to areforming reaction and not giving any damage such as deterioration ordestruction to the porous Ni-containing catalyst by a solid-phasereaction or the like, for instance, the same material as theNi-containing catalystic portion can be used, or it is possible to usematerial of at least one or two kinds or more of metal(s) selectedinvariably containing Ni or Ru from Ni, Ru, Rh, Pd, Re, Os, Ir or Ptsupported by a non-magnesia catalyst support. As an example of compositematerial of catalyst and ceramics of the present invention placing theparticle size adjusted reforming catalyst portion in its neighbor,material that particles of a particle size adjusted reforming catalystare filled in the inside of a catalized ceramic composite tube preparedby laminating a porous Ni-containing catalyst layer in the insidesurface thereof (coated and fired to join firmly) can be cited.

[0138] The reason to limit the average pore size and thickness of theporous Ni-containing catalyst layer, and the particle size of theparticle size adjusted reforming catalyst portion is as follows. Whenthe average pore size of a porous Ni-containing catalyst layer exceeds10 μm, it becomes mechanically weak, which makes it difficult to be putinto practical use. On the contrary, a porous Ni-containing catalystlayer having an average pore size of 10 μm or less is mechanicallystrong. Further, when thickness of the porous layer is less than 0.01mm, it is unfavorable because a sufficient catalytic function may not beobtained in the case when methane-containing gas has a pressure of 0.5MPa or less, and sometimes it causes exfoliation when the thicknessexceeds 1 mm. On the other hand, when the thickness is in the range of0.01 mm to 1 mm, a relatively sufficient catalytic function can beobtained and the porous layer is hard to be peeled. Especially in therange of 0.1 mm to 0.5 mm in thickness, a sufficient catalytic functioncan be obtained, and no exfoliation occurs at all. The reason oflimiting the particle size of the particle size adjusted reformingcatalyst portion to be 0.5 mm or more is that if the particle size isless than 0.5 mm, a gas channel becomes narrow to serve as resistanceagainst gas flow, and if the particle size adjusted reforming catalystportion is thick, exchange of gases may not be performed rapidly, inother words, production of synthetic gas may be restrained.

[0139]FIG. 5 is a sectional view showing a structure of compositematerial of catalyst and ceramics relating to the third embodiment ofthe third invention. In the third embodiment, a reforming catalystportion 14 is formed on a porous layer 12 being a catalyst portion.

[0140] The composite material of catalyst and ceramics relating to thethird invention can keep high oxygen permeability without the denseceramic membrane being destroyed by reductive expansion and the like tobe able to produce synthetic gas stably for a long time. The thinner thedense ceramic membrane becomes, the more the oxygen permeation rate, orthe production rate of synthetic gas increases. However, when it becomesthin to some extent, an interface reaction on the air (cathode) sideapproaches a rate-determining stage to restrain increase of the oxygenpermeation rate. In such a case, it is effective to join firmly a porouslayer consisting of oxygen ion-electron mixed conducting oxide selectedindependently from material of the dense ceramic membrane, thecomposition being expressed by composition formula (formula 2) andhaving a perovskite structure, to the second surface (air-containing gasside surface) of dense ceramic membrane of the composite material ofcatalyst and ceramics relating to the present invention. Then, since areaction area causing a cathodic reaction increases dramatically, it ispossible to avoid rate determination of the cathodic reaction. Thismaterial has high activity to a cathodic reaction. Besides, thismaterial does not deteriorate due to crystal transformation, and doesnot cause lowering of cathodic reaction rate even by being exposed to anatmosphere having a high partial pressure of oxygen such as highpressure air or the like. This is because Nb and/or Ta contained in Bsite is or are thought to have a function to forcibly stabilize theperovskite structure. Note that the dense ceramic membrane and theporous layer may be the same as or different from each other incomposition so far as their compositions are expressed by thecomposition formula 2.

[0141] In the composite material of catalyst and ceramics relating tothe third invention, porosity of the porous layer is preferably in therange of 20% to 80%, and more preferably 30% to 70%. As for thickness,it is preferable to be 0.001 mm to 5 mm, more preferably 0.01 mm to 1mm, much more preferably 0.05 mm to 0.5 mm. If the porosity is set to beless than 20%, or if the thickness is set to be more than 5 mm, it isunfavorable because resistance against gas flow in the porous layer isincreased, and increase of oxygen permeation rate, or production rate ofsynthetic gas is restrained. If the porosity exceeds 80%, it isunfavorable because the porous layer becomes mechanically weak and itbecomes impossible to join the porous layer with the dense ceramicmembrane material firmly. Further, when the thickness is less than 0.001mm, since increase of a reaction area is not sufficient, the oxygenpermeation rate, or the production rate of synthetic gas is not sodifferent from the rate without the porous layer, and therefore, apromotion effect of the cathodic reaction, which is an aim with theporous layer, cannot be obtained.

[0142] In the composite material of catalyst and ceramic relating to thethird invention, as a catalyst portion contiguous to the dense ceramicmembrane, as explained before, material containing Ni as a maincomponent of active metal is used to a catalyst support mainly composingof magnesia. As the Ni-containing catalyst, one kind or two kinds ofelement(s) selected invariably containing Ni from Ni and Mn is supportedby a support mainly composed of magnesia by an impregnation holdingmethod can be used, or as an average composition, a compositionexpressed by the composition formula (formula 6) can be used.

Ni_(rni)Mn_(rmn)Mg_(1−rni−rmn)O_(c)  (formula 6)

[0143] (Wherein the range of rni fulfills 0<rni≦0.4, the range of rmnfulfills 0≦rmn≦0.1. c is a value determined to fulfill the condition ofneutral electric charge.)

[0144] In the case of the former, it shows catalytic activity stablywhen a pressure of methane-containing gas is at least from a normalpressure to 2 MPa. In the case of the latter, the composition is aso-called solid solution catalyst in which Ni or NiO_(x) is dissolved inmagnesia in a solid solution state in a catalyst adjusting stage andbecomes a hydrocarbon-reforming catalyst in a manner that a Ni-componentis reduced to metal Ni by placing the same in a reductive circumstance.On the other hand, according to conditions of reaction such as theamount of water vapor introduced to methane-containing gas from outsidebeing too small or like, Ni is excessively reduced, so that there arisesa problem of growth of Ni particles which finally leads to increasecarbon deposition property. For this problem, the present inventorsconfirmed by experiments that it is suitable to use a catalyst allowingMn which is high in oxygen dissociation property to dissolve in amagnesia series catalyst in a solid-solution state, which is disclosedin Japanese Patent Application Laid-open 2000-288394 and the like.Generally, a solid solution catalyst is reduction-resistant but thepresent inventors found that the solid solution catalyst startsreduction and displays activeness as a hydrocarbon-reforming catalyst inthe case of the aforementioned composition, by adopting a temperature toabout 900° C. and a pressure of methane-containing gas to 0.5 MPa ormore, and in the case of co-existing of one kind or two kinds or more ofmetal(s) selected from a group consisting of Ru, Rh, Pd, Re, Os, Ir andPt in a range of 2 wt % or less, by setting a pressure ofmethane-containing gas to 0.3 MPa or more.

[0145] It is possible to reduce in a similar manner as described aboveeven Mn is contained in a catalyst expressed by a formulaNi_(rni)Mn_(rmn)Mg_(1−rni−rmn)O, though it takes somewhat a long time.The aforementioned method of reduction has a merit that activation ofthe Ni_(rni)Mn_(rmn)Mg_(1−rni−rmn)O catalyst can be performed only byplacing a composite material of catalyst and ceramics relating to thethird invention prepared by stacking Ni_(rni)Mn_(rmn)Mg_(1−rni−rmn)Ocatalyst layer under synthetic gas producing conditions as a partitionmembrane, and increasing a pressure on the methane-containing gas sidewithout reducing the dense ceramic membrane, and is suitable for theobject of the third invention. In a solid solution catalyst obtained ina manner described above, Ni is dispersed in an extremely high state andcatalytic activity is high and carbon precipitation property is low.However, since the catalytic activity is sometimes low when a pressureof methane-containing gas is less than 0.3 MPa, caution should be takenwhen in use.

[0146] In the case of Ni-supporting catalyst, a supporting amount in therange of 5 wt % to 40 wt % is preferable, and 10 wt % to 30 wt % is morepreferable. This is because that the catalytic activity is insufficientat the supporting amount of less than 5 wt %, and the catalytic activityis saturated and the carbon precipitation property is increased at thesupporting amount of more than 40 wt %.

[0147] The composition range of Ni and magnesia solid solution catalystNi_(rni)Mn_(rmn)Mg_(1−rni−rmn)O is 0<rni≦0.4, and 0≦rmn≦0.1 as describedabove. The values of rni and rmn are preferably in the range of0.05<rni≦0.3, and 0≦rmn≦0.08 respectively, and more preferably in therange of 0.1≦rni≦0.2, and 0≦rmn≦0.06. This is because in the case ofrni>0.4, the catalytic activity is saturated and the carbonprecipitation property is increased.

[0148] In the composite material of catalyst and ceramics relating tothe third invention, as a catalyst other than the above, for instance,the following materials can be used.

[0149] (e) It is possible to use a catalyst portion including materialsupporting one kind or two kinds of element(s) selected invariablycontaining Ni from Ni and Mn on a support mainly composed of magnesia ora composition expressed by formula 6 as an average composition, and acomposite oxide, whose composition is expressed by formula 2 andselected independent of the dense ceramic membrane or porous material.

[0150] (f) It is possible to use a catalyst portion including materialsupporting one kind or two kinds of element(s) selected invariablycontaining Ni from Ni and Mn on a support mainly composed of magnesia ora composition expressed by formula 6 as an average composition, furthersupporting one kind or two kinds or more of metal selected from a groupconsisting of Ru, Rh, Pd, Re, Os, Ir and Pt in the range of 2 wt % orless.

[0151] (g) It is possible to use a catalyst portion including materialsupporting one kind or two kinds of element(s) selected invariablycontaining Ni from Ni and Mn on a support mainly composed of magnesia ora composition expressed by formula 6 as an average composition, furthersupporting one kind or two kinds or more of metal selected from a groupconsisting of Ru, Rh, Pd, Re, Os, Ir and Pt in the range of 2 wt % orless, and a composite oxide, whose composition is expressed by formula 2and selected independently from the dense ceramic membrane or porousmaterial.

[0152] The composite oxide expressed by formula 2 described in (e)serves as an oxidative catalyst of hydrocarbon such as methane and thelike and produces CO₂ and H₂O. Accordingly, a partial pressure of oxygennear the interface between the dense ceramic membrane and catalystportion becomes moderately high, serving to prevent deterioration anddestruction of the dense ceramic membrane. Since Ni-containing catalystof which catalyst support is mainly composed of magnesia is difficult tocause a solid-phase reaction between magnesia and dense ceramicmembrane, they sometimes do not join successively or firmly whenstacking them (when being contiguous to each other). However, thecomposite oxide expressed by formula 2 also has a function to join thecatalyst portion and the dense ceramic membrane more firmly. Since thecomposite oxide expressed by formula 2 contains Nb, Ta, In and Y, it isexcellent in reduction-resistance. When the reduction-resistance isespecially enhanced, it is recommendable to increase the content of Nb,Ta, In, Y and Fe within a predetermined compositional range. When thedefined compositional range is exceeded, it is unfavorable because thefunction and reduction-resistance as an oxidation catalyst are lowered.

[0153] The one kind or two kinds or more of metal(s) selected from thegroup consisting of Ru, Rh, Pd, Re, Os, Ir and Pt described in (f)serve(s) as a highly active reforming catalyst to hydrocarbon, andproduces CO and H₂ from hydrocarbon such as methane or the like, CO₂ andH₂O at a high rate. Accordingly, these metals increase a production rateof synthetic gas more compared to the case when active metal is Nialone. However, since all metals are expensive noble metals, it isnecessary to determine the supporting amount to be minimum, and it ispreferable for the supporting amount to be 2 wt % or less, morepreferably 1 wt % or less, and much more preferably 0.5 wt % or less. Itshould be noted that since a Ni-containing catalyst in which a maincomponent of the catalyst support is magnesia is hard for magnesia toperform a solid-phase reaction with the dense ceramic membrane, itsometimes does not join successfully (put to be contiguous) whenstacking, but the above-described supporting metal also has a functionto join the catalyst portion and the dense ceramic membrane more firmly.

[0154] The catalyst portion described in (g) is a combination of (e)with (f), and it has a specific feature of high production rate ofsynthetic gas. Other specific features, operation, requirement and so onare as explained before.

[0155] As already explained, it is possible to produce synthetic gaswith high energy efficiency, at low cost, and stably for a long periodof time by using a partition membrane consisting of the compositematerial of catalyst and ceramics of the third invention, and making thecatalyst portion side under methane-containing gas atmosphere, and theopposite side thereof under air or oxygen-containing gas atmosphere. Adesirable production method is to set a temperature normally to 850° C.or more, preferably about 900° C., and adopt the following conditions.

[0156] (h) When a porous layer structure (porous Ni-containing catalystlayer) having a Ni-containing catalyst portion of 10 μm or less inaverage pore diameter and 0.01 mm to 1 mm in thickness is joined to thefirst surface firmly, a pressure of methane-containing gas on thecatalyst portion side is set to 0.3 MPa or more.

[0157] (i) When a porous layer structure (porous Ni-containing catalystlayer) having a Ni-containing catalyst portion of 10 μm or less inaverage pore diameter and 0.01 mm to 1 mm in thickness is joined to thefirst surface firmly, and further, a reforming catalyst portion(particle size adjusted reforming catalyst portion) whose particle sizeis adjusted to 0.5 mm or more is placed contiguous to theabove-described porous layer structure, a pressure of methane-containinggas on the catalyst portion side is set to 0.5 MPa or less.

[0158] (j) Water vapor is allowed to contain in methane-containing gasfrom outside, and the concentration ratio of the water vapor to methaneis set in the range of 2 or less.

[0159] The reason of the conditions (h) being desirable is no particlesize adjusted reforming catalyst portion is required because thereforming reaction can be advanced rapidly even with a comparativelysmall catalyst, when a pressure of the raw material methane-containinggas is 0.3 MPa or more, or preferably 0.5 MPa or more.

[0160] The reason of the conditions (i) being desirable is because whenthe raw methane-containing methane gas is 0.5 MPa or less, a reformingreaction rate is relatively slow, and it is necessary to complete thereforming reaction by making the reforming reaction advance also in theparticle size adjusted reforming catalyst portion in addition to theporous Ni-containing catalyst layer. When the raw materialmethane-containing gas is 0.5 MPa or less, the content of CO and H₂contained in synthetic gas sometimes becomes low unless doing so. Itshould be noted that when the raw material methane-containing gas is 0.5MPa or less, a carbon precipitation reaction to be described later ishard to occur, and therefore, no remarkable precipitation of carbonoccurs even the particle size adjusted reforming catalyst portion isplaced to be contiguous. As a particle size adjusted reforming catalystportion, various Ni-containing catalytic materials already explained asthe essential constituents of the composite material of catalyst andceramics relating to the third invention, and/or one kind or two kindsor more of metal(s) selected invariably containing Ni or Ru from thegroup consisting of Ni, Ru, Rh, Pd, Re, Os, Ir, or Pt which is supportedby a non-magnesia catalyst support, can be used. These are high inability as a reforming catalyst.

[0161] The reason of the conditions (j) being desirable is to restrain acarbon precipitation reaction which may occur as a sub-reaction on thereforming catalyst for hydrocarbon such as methane or the like (aNi-containing catalyst portion, a porous Ni-containing catalyst layer,or a particle size adjusted reforming catalyst portion in the thirdinvention). Since the carbon precipitation reaction easily occurs when amethane-containing gas pressure gets high, the conditions (j) are usefulespecially when producing synthetic gas under the conditions of (h).When the concentration ratio of water vapor and methane exceeds 2,precipitation of carbon is restrained. However, it is unfavorablebecause a Ni catalyst is easy oxidized in a wide area of theNi-containing catalyst portion, which leads to increase of the partialpressure of oxygen near the dense ceramic membrane surface to result inlowering of oxygen permeation rate. On the contrary, when theconcentration ratio of water vapor and methane is 2 or less, such athing does not occur and synthetic gas can be produced while a carbonprecipitation reaction is being restrained.

[0162] Next, an example of production method of third invention-relatedmaterial will be explained. The raw material of dense ceramic membraneis prepared by using metallic oxides or metal salts such as carbonates,and by mixing and sintering them. For preparation of powder material, itis acceptable to use a co-precipitation method, a metal alkoxide method(sol-gel method), or method of preparation equivalent to these methods.Mixed raw material powder is calcinated at a predetermined temperature,and the sample after calcination is finely pulverized and molded afterthe pulverized powder is uniformly mixed. For the molding, any suitableceramic production technology such as CIP (cold isostatical press), HIP(hot isostatical press), mold press, injection molding method, slipcasting method, extrusion molding method, and so on can be applied, anda molded sample is sintered at high temperatures.

[0163] The porous layer is prepared by main sintering at hightemperatures without molding which is different from the dense ceramicmembrane, after preparation of raw material, mixing, calcinations andcrushing. It is also acceptable to omit the intermediate calcination andperform main sintering directly if the raw material is uniformly mixed.At the time of main sintering, it is necessary to adopt a sinteringtemperature which realizes a perovskite structure to display mixedconductivity. The sintered sample is finely powdered by an appropriatemethod such as a ball mill or the like.

[0164] The porous layer is formed by slurry-coating with theabove-described sample using an organic solvent or the like to cover thedense continuous layer surface. Generally, the uniformly smaller theparticle size of the powder applied by coating or the thinner thepowder, the more uniformly the powder can be attached on the membranesurface. As a molding method other than these described above, CVD(chemical deposition) method, electrophoresis, sol-gel method, or anyother suitable methods can be used. The porous layer formed by thesemethods is sintered so as to join the porous layer and the dense ceramicmembrane firmly to ensure continuity in mixed conductivity on theinterface with the dense ceramic membrane. As the sintering temperature,a suitable temperature is selected, which is below the melting point ofeither material for the porous layer or for the dense ceramic membranehaving a melting point lower than the other, and the temperature atwhich firm joining can be obtained.

[0165] Ni-containing catalyst is prepared by a co-precipitation method,ceramics method, or the like, and when minute amount of noble metalssuch as Ru, Rh, Pd, Re, Os, Ir, Pt and so on is supported to theNi-containing catalyst, a suitable method is selected from animpregnation holding method, an equilibrium adsorption method and so on.

[0166] In order to join the catalyst firmly on the surface of the denseceramic membrane, fine powder of the composite oxide expressed byformula 2 is added to the finely pulverized powder of the catalystprepared as above, and mixed thoroughly. The mixture is suspended in anorganic solvent or the like, the suspension is slurry-coated on thedense ceramic membrane surface, and it is desirable to sinter it in theair at a temperature at least 50° C. higher than the actual operationtemperature of a membrane reactor and below the melting point of theceramic material. At this time, the fine powder of the composite oxideis preferably 0.1 or less in mole ratio to the prepared catalystdescribed above, more preferably, 0.05 or less, and much more preferably0.03 or less. The weight of the catalyst after firing per unit membranearea is suitably 20 to 50 mg/cm². In order to adjust the particle sizeof the catalyst, a suitable method such that finely crushed powder ispressed, pulverized and then the particle size is made uniform with asieve, and so on is selected.

[0167] The production method described above relates to making aself-supporting membrane of material of the present invention.Hereinafter, a production method of joining the material of the presentinvention to a porous substrate as a covering layer will be explained.For the production of a porous body according to the present invention,a ceramics method, co-precipitation method, alkoxide method and so onusually used for producing a ceramics porous body can be used. Sinteringof the porous body is usually performed by dividing it into two steps ofcalcinating and main firing (sintering). As for calcination temperaturerange, it is usually conducted in the range of 400 to 1000° C., for fromseveral hours to ten and several hours. The calcinated powder can bemolded directly and sintered, or can be mixed with resin such aspolyvinyl alcohol (PVA) and the like, molded and sintered. While themain sintering temperature is usually a maximum heat treatmenttemperature for producing the porous body, the main sinteringtemperature of the porous body provided by the present invention is inthe range of 700 to 1450° C., preferably in the range of 1000 to 1350°C. For the sintering, it usually requires several hours or more. As anatmosphere for the main sintering, it is usually sufficient to beconducted in the air, but it is acceptable to sinter under a controlledatmosphere as necessary. As a molding method for the porous body, it ispossible to pack the calcinated powder or mixed powder into a diesimilarly to a typical bulk ceramics production, pressurize and mold. Itis also possible to use a slurry casting method, extrusion moldingmethod, and the like.

[0168] On the other hand, the dense ceramic membrane can be produced bya typical method for producing a ceramic membrane. It is possible tomake the membrane by a so-called thin film forming method such as PVD orCVD of a vacuum deposition method and the like. However, it ispreferable from economical point of view to apply coating on the porousbody with a slurried raw material powder or calcinated powder and tosinter. Usually, the temperature of sintering the dense ceramic membranecorresponds to the maximum heat treatment temperature for membraneproduction. However, it is also required to make the membrane dense lestgas leakage should occur, and select a condition under which porosity ofthe porous body is not greatly lowered during the sintering process. Forthis reason, the sintering temperature of the dense ceramic membrane ispreferably about densification temperature of the material constitutingthe membrane, and for the sintering, several hours are usually required.A method of joining the catalyst firmly on the dense ceramic membranesurface is conducted similarly to the case of the self-supportingmembrane.

[0169] Next, an embodiment of the third invention will be explained.However, this is purely for the purpose of explaining an experiment, andthe scope contained in the third invention is not limited to thiscontent.

Experiment 1 of the Third Invention (Preparation of Material)

[0170] Commercially available powder of BaCO₃, CoO, Fe₂O₃ and Nb₂O₅having purity of 99% or more was weighed to be a mole ratio ofBa:Co:Fe;Nb=1:0.7:0.2:0.1, and wet mixed for two hours using a planetaryball mill. Obtained material powder was put in a crucible made ofalumina, and calcinated at 950° C., for 20 hours in the air to obtaincomposite oxide. After the composite oxide was wet pulverized for twohours with a planetary ball mill, 3 g of the powder was molded in a diskshape at 25 MPa with a mold of 20 mm in diameter. The molded body wasput in an airtight bag and degassed to make a vacuum. Then whileapplying pressure to 200 MPa, CIP was given for 15 minutes, and mainsintering was conducted for 5 hours at 1130° C. to obtain a densifiedsintered body having a relative density of 95% or more. A result ofperforming powder X-ray diffraction measurement of the sintered body atroom temperature showed that its main component is a cubic perovskitestructure and it was confirmed that it is a composite oxide expressed bythe composition of BaCO_(0.7)Fe_(0.2)Nb_(0.1)O_(3−δ). Both sides of thesintered body was ground and polished to make a disk shape of 12 mm indiameter, and 0.7 mm in thickness to be used as a dense ceramicmembrane. The same sintered body as that described above, expressed by acomposition of BaCO_(0.7)Fe_(0.2)Nb_(0.1)O_(3−δ) was pulverized andsuspended in an organic solvent to be a slurry and applied on the denseceramic membrane surface. After drying this for 5 minutes at 120° C., adense ceramic membrane (ceramic membrane A) to which a porous layerfirmly joined with a dense ceramic membrane surface was added, wasobtained by sintering for five hours at 1050° C. in the air.

[0171] A mixed aqueous solution of nickel acetate and magnesium nitratewas prepared to obtain a mole ratio of Ni:Mg=0.1:0.9, and by adding apotassium carbonate aqueous solution, precipitate consisting of twocomponents of nickel and magnesium was produced. After filtrating theprecipitate and washing it, the precipitate is dried for 12 hours ormore at 120° C. in the air. Then, it was sintered for 20 hours at 1000°C. in the air to obtain a nickel and magnesia catalyst (catalyst A)expressed by Ni_(0.1)Mg_(0.9)O.

[0172] Commercially available powder of SrCO₃, Fe₂O₃ and Nb₂O₅ havingpurity of 99% or more was weighed to be a mole ratio ofSr:Fe:Nb=1:0.9:0.1, and wet mixed for two hours using a planetary ballmill. Obtained material powder was put in a crucible made of alumina,and calcinated at 1350° C., for 5 hours in the air to obtain compositeoxide. A result of performing powder X-ray diffraction measurement ofthe composite oxide at room temperature showed that its main componentis a cubic perovskite structure and it was confirmed that it is acomposite oxide expressed by the composition ofSrFe_(0.9)Nb_(0.1)O_(3−δ). The composite oxide was wet pulverized fortwo hours with a planetary ball mill to obtain composite oxide formethane reforming catalyst lamination layer.

[0173] The composite oxide for methane reforming catalyst laminationlayer was added to fine powder of the catalyst A at a mole ratio of 0.02and mixed thoroughly and thereafter, the mixture was suspended in anorganic solvent to slurry-coat on the surface of the opposite side tothe porous layer of the ceramic membrane A. After drying this for 5minutes at 120° C., the composite material A of catalyst and ceramicswhich was prepared by joining a methane reforming catalyst firmly on thedense ceramic membrane surface by sintering for 5 hours at 1050° C. inthe air was obtained. At this time, weight of the catalyst per unitsurface area of the ceramic membrane was 30 mg/cm².

Experiment 2 of the Third Invention (Material Preparation)

[0174] Commercially available powder of BaCO₃, SrCO₃, CoO, Fe₂O₃ andTa₂O₅ having purity of 99% or more was weighed to be a mole ratio ofBa:Sr:Co:Fe:Ta=0.8:0.2:0.7:0.2:0.1, and a dense ceramic membraneexpressed by the composition ofBa_(0.8)Sr_(0.2)Co_(0.7)Fe_(0.2)Ta_(0.1)O_(3−δ) was obtained in asimilar manner as in experiment 1. Further, a dense ceramic membrane(ceramic membrane B) to which a porous layer firmly joined to a denseceramic membrane surface expressed by the composition ofBa_(0.8)Sr_(0.2)Co_(0.7)Fe_(0.2)Ta_(0.1)O_(3−δ) was added in a similarmanner as in experiment 1. Then, on a surface opposite to the porouslayer of the ceramic membrane A, a methane reforming catalyst is firmlyjoined using a similar method to experiment 1 to obtain a compositematerial B of catalyst and ceramics.

Experiment 3 of the Third Invention (Material Preparation)

[0175] Using a similar manner to experiment 1 except that oxide formethane reforming catalyst lamination layer (composite oxide expressedby the composition of SrFe_(0.9)Nb_(0.1)O3−δ in experiment 1) is notused on a surface (a first surface) opposite to the porous layer of theceramic membrane 1 described in experiment 1, a methane reformingcatalyst was sintered on the surface of a ceramic membrane and it wasconfirmed that Ni-containing catalyst portion was joined to a denseceramic membrane. However, the bonding strength was rather smallcompared to that of the composite material A of catalyst and ceramics,and a function of bonding strengthening due to co-existing of oxide formethane reforming catalyst lamination layer was recognized.

Experiment 4 of the Third Invention (Experiment of High-pressureSynthetic Gas Production)

[0176] The composite material A of catalyst and ceramics was sandwichedbetween a metal tube (made of Inconel 600, providing a slit-shape gasexhaust port on the composite material side of catalyst and ceramics ofthe tube) and a mullite pipe to be installed on an experimentalapparatus. At this time, a silver O ring was disposed between themullite pipe and the above-described composite material of catalyst andceramics, and they were heated to about 950° C. in an electric oven tofuse them so that airtightness between the mullite pipe and thecomposite material of catalyst and ceramics was ensured. The productionexperiment of synthetic gas was carried out as follows. 200 cc/min ofair was fed from a charging tube inside a metal tube under theconditions of temperature at 900° C., with a pressure of 10 atm (about1.013×10⁻⁴ Pa), and 60 cc/min of methane was fed from a charging tubeinside the mullite pipe. Then, a reaction product on the methane sidewas analyzed by gas chromatography. The element balance was applied tothe composition of the product measured by gas chromatography, and astable oxygen permeation rate after 100 hours of elapsed time frombeginning of the experiment from air side to methane side wascalculated.

[0177] As a result, an oxygen permeation rate was 20 cc/min/cm². At thistime, reaction conversion ratio of methane, CO selection ratio (CO ratioin CO and CO₂), H₂/CO ratio were 54%, 80%, and 2.0, respectively. Changein quality of the material used, and carbon precipitation on thecatalyst were not observed after the experiment.

Comparison 1 of the Third Invention (Experiment of High-PressureSynthetic Gas Production)

[0178] A production experiment of synthetic gas was carried out in asimilar manner to experiment 4 except mixing 150 cc/min of water vaporinto methane. As a result of calculating a stable oxygen permeation rateafter 100 hours of elapsed time from beginning of the experiment, it wasfound to be 8 cc/min/cm². Change in quality of the material used, andsignificant carbon deposition on the catalyst was not observed after theexperiment.

Experiment 5 of the Third Invention (Experiment of High-PressureSynthetic Gas Production)

[0179] A production experiment of synthetic gas was carried out in asimilar manner to experiment 4 except using the composite material B ofcatalyst and ceramics. As a result of calculating a stable oxygenpermeation rate after 100 hours of elapsed time from beginning of theexperiment, it was found to be 19 cc/min/cm². At this time, reactionconversion ratio of methane, CO selection ratio (CO ratio in CO andCO₂), H₂/CO ratio were 52%, 81%, and 2.0, respectively. Change inquality of the material used, and carbon precipitation on the catalystwere not observed after the experiment.

Comparison 2 of the Third Invention (Experiment of High-PressureSynthetic Gas Production)

[0180] Commercially available powder of BaCO₃, SrCO₃, CoO, and Fe₂O₃having purity of 99% or more was weighed to be a mole ratio ofBa:Sr:Co:Fe=0.5:0.5:0.8:0.2, and a dense ceramic membrane expressed bythe composition of Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3−δ) was added wasobtained in a similar manner as in experiment 1. Further, a denseceramic membrane (ceramic membrane C) to which a porous layer firmlyjoined to a dense ceramic membrane surface expressed by the compositionof Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3−δ) was added was obtained in asimilar manner as in experiment 1.

[0181] Commercially available powder of SrCO₃, CoO, and Fe₂O₃ havingpurity of 99% or more was weighed to be a mole ratio ofSr:Co:Fe=1:0.8:0.2, and a dense ceramic membrane expressed by thecomposition of SrCo_(0.8)Fe_(0.2)O_(3−δ) was obtained in a similarmanner as in experiment 1. Further, a dense ceramic membrane (ceramicmembrane D) to which a porous layer firmly joined to a dense ceramicmembrane surface expressed by the composition ofSrCo_(0.8)Fe_(0.2)O_(3−δ) was added was obtained in a similar manner asin experiment 1.

[0182] Commercially available Al₂O₃ powder having purity of 99% or morewas sintered for 5 hours at 1100° C. in the air to obtain α-alumina,which was wet-pulverized with a planetary ball mill to serve as acatalyst support. Then, the catalyst support was immersed in a nickelnitrate aqueous solution to hold Ni as a Ni-impregnated support.Subsequently, after Ni-impregnated catalyst support was dried thoroughlyin the air, it was sintered for 5 hours at 1000° C. in the air to obtaina catalyst (catalyst B) expressed by Ni 10 wt %/Al₂O₃.

[0183] By adding a potassium carbonate aqueous solution to a magnesiumnitrate aqueous solution, a precipitate composing of magnesium componentis generated. After the precipitate was filtered and washed, it wasdried for 12 hours at 120° C. in the air. Thereafter, it was sinteredfor 2 hours at 1000° C. in the air, and used as a catalyst support.Then, it was immersed in a ruthenium (III) chloride aqueous solution for20 hours while keeping pH constant by a magnesium hydroxide aqueoussolution, and Ru was adsorbed in equilibrium to the catalyst support andfiltrated to obtain a Ru-adsorbed catalyst support. Next, after theRu-adsorbed catalyst support was thoroughly dried in the air, it wassintered for 5 hours at 1000° C. in the air to obtain a catalyst(catalyst C) expressed by a formula Ru 2 wt %/MgO.

[0184] As for combinations shown in Table 4 relating to ceramicmembranes A to D and catalysts A to D, composite materials of catalystand ceramics were prepared in a similar manner to experiment 1 exceptthat no oxide for methane reforming catalyst lamination layer was used,and a production experiment of synthetic gas was carried out in asimilar manner to experiment 4 using these materials. As a result, theoxygen permeation rate was reduced in all cases during period of time,and could not obtain a stable oxygen permeation rate within 100 hoursafter the experiment began.

Experiment 6 of the Third Invention (Production Experiment of MediumPressure Synthetic Gas)

[0185] Fine powder of the catalyst A is immersed in an acetone solutionof rhodium acetylacetonade and acetone was vaporized at 70° C.Thereafter, it was dried for 12 hours or more at 120° C., and thecatalyst (catalyst D) expressed by Rh 1 wt %/Ni_(0.1)Mg_(0.9)O wasobtained. Then, the catalyst D was finely pulverized, and pressed undera pressure of 2 ton/cm² (about 1.96×10⁸ Pa). Thereafter, the particlesize was adjusted to 20/40 mesh to obtain the particle size adjustedcatalyst A.

[0186] Similarly to experiment 1 except using the catalyst D instead ofthe catalyst A, a composite material C of catalyst and ceramics in whicha methane reforming catalyst was firmly joined on the dense ceramicmembrane surface was obtained. Then, 950 mg/cm₂ of the particle sizeadjusted catalyst A was filled on the methane reforming catalyst layerside of the composite material C of catalyst and ceramics disposed in anexperimental apparatus, and a production experiment of synthetic gas wascarried out similarly to experiment 4 except 3 atm (3.040×10⁵ Pa) ofpressure. A calculated result of a stable oxygen permeation rate just100 hours after the beginning of the experiment was found to be 25cc/min/cm². At this time, reaction conversion rate of methane, COselection rate (CO ratio in CO and CO₂), H₂/CO ratio were 76%, 95%, and2.0, respectively. Change in quality of the material used, andsignificant carbon precipitation on the catalyst were not observed afterthe experiment.

Experiment 7 of the Third Invention (Production Experiment ofLow-Pressure Synthetic Gas)

[0187] Precipitate consisting of magnesium component was created byadding a potassium carbonate aqueous solution to a magnesium nitrateaqueous solution. The precipitate was filtrated and washed. Then, theprecipitate was dried for 12 hours or more at 120° C. in the air. Then,it was sintered for 2 hours at 1000° C. in the air and used for acatalyst support. Next, the catalyst support was immersed in a nickelnitrate aqueous solution to hold Ni. Subsequently, after theNi-impregnated catalyst support was dried thoroughly in the air, it wassintered for 5 hours at 1000° C. in the air to obtain a catalyst(catalyst E) expressed by Ni 10 wt %/MgO. Then, the catalyst E wasfinely pulverized, and pressed under a pressure of 2 ton/cm² (about1.96×10⁸ Pa). Thereafter, the particle size was adjusted to 20/40 meshto obtain the particle size adjusted catalyst B.

[0188] Similarly to experiment 1 except using the catalyst E instead ofthe catalyst A, a composite material D of catalyst and ceramics in whicha methane reforming catalyst was firmly joined on the dense ceramicmembrane surface was obtained. Then, 950 mg/cm₂ of the particle sizeadjusted catalyst B was filled on the methane reforming catalyst layerside of the composite material D of catalyst and ceramics disposed in anexperimental apparatus similarly to experiment 4, and a productionexperiment of synthetic gas was carried out similarly to experiment 3except that atmospheric pressure was applied as the pressure. Acalculated result of a stable oxygen permeation rate just 100 hoursafter the beginning of the experiment was 22 cc/min/cm². At this time,reaction conversion rate of methane, CO selection rate (CO ratio in COand CO₂), H₂/CO ratio were 77%, 97%, and 2.0, respectively. Change inquality of the material used, and significant carbon precipitation onthe catalyst were not observed after the experiment.

Experiment 8 of the Third Invention (Production Experiment ofLow-Pressure Synthetic Gas)

[0189] Ceramic material shown in Table 5 was produced in a mannersimilar to experiment 2 to obtain a composite material of catalyst andceramics in which a methane reforming catalyst was firmly joined on thedense ceramic membrane surface was obtained similarly to that inexperiment 7. Using this, a production experiment of synthetic gas wascarried out in a manner similar to experiment 7. The result ofcalculating a stable oxygen permeation rate 100 hours after beginning ofthe experiment was shown in Table 5.

Comparison 3 of the Third Invention (Production Experiment ofLow-Pressure Synthetic Gas)

[0190] A ceramic membrane containing a porous layer was obtained in amanner similar to experiment 1 except no application of slurry coat on asurface of the opposite side to the porous layer of ceramic membrane Awith a methane reforming catalyst. Using this ceramic membrane, aproduction experiment of synthetic gas was carried out similarly toexperiment 7. The result of calculating a stable oxygen permeation rate100 hours after beginning of the experiment was 17 cc/min/cm². At thistime, reaction conversion rate of methane, CO selection rate (CO ratioin CO and CO₂), H₂/CO ratio were 53%, 98%, and 2.0, respectively. Changein quality of the material used, and significant carbon precipitation onthe catalyst were not observed after the experiment.

Comparison 4 of the Third Invention (Production Experiment ofLow-Pressure Synthetic Gas)

[0191] A production experiment of synthetic gas was carried outsimilarly to experiment 4 except that atmospheric pressure was appliedas the pressure. A calculated result of a stable oxygen permeation rate100 hours after the beginning of the experiment was 8 cc/min/cm².

Industrial Applicability

[0192] As described above in detail, according to the first invention,in a perovskite structure oxide ion mixed conductor, a ceramiccomposition high in the ratio of Ba in A site, a cubic perovskitestructure being sufficiently stable, and showing a high oxygenpermeation rate, can be realized. Further, the ceramic composition isapplied in a technical field such as selective permeation of oxygen andseparation process by an oxide ion mixed conductor or a partitionmembrane reactor for partial oxidation of hydrocarbon and the like sothat excellent oxygen permeation characteristic can be displayed. Theceramic composition is also suitable for a dense continuous layer of acomposite material used for oxygen-separation apparatus and the like, aporous substrate, or a catalyst. A technology provided by the firstinvention contributes greatly to make oxygen-separation apparatus fromair and a partition membrane reactor high performance and low cost.

[0193] According to the second invention, a high performance partitionmembrane member to stably obtain a high oxygen permeation rate isobtained when an oxygen component in an oxygen-containing gas isselectively transferred. Accordingly, it is suitably used to a membranereactor for synthetic gas production by partial oxidation of hydrocarbonand the like to contribute to make it compact leading to improve theperformance and cost of the apparatus.

[0194] According to the third invention, synthetic gas can be producedwith high energy efficiency, low cost, and long term stability, withoxygen-containing gas such as air and hydrocarbon-containing gas such asmethane as raw material, using a partition membrane having a structurewhich integrates a dense oxygen selective permeation ceramic membraneand a methane reforming catalyst layer. It should be noted that as a gascontaining raw material methane, recycle gas of natural gas, coalfieldgas, coke-oven gas, or gas obtained by Fischer-Tropsch syntheticreaction, or, reforming gas of natural gas, coalfield gas, coke-ovengas, LPG, naphtha, gasoline, or kerosene can be used. TABLE 1 1-rc-rd-re- No rba1 XA α XB rf XC rc  1 0 Sr 1 Co 0.9 In 0.1 Comparison  20.4 Sr 1 Co 0.9 In 0.1 Experiment  3 0.6 Sr 1 Co 0.9 In 0.1 Experiment 4 0.8 Sr 1 Co 0.9 In 0.1 Experiment  5 0.9 Sr 1 Co 0.9 In 0.1Experiment  6 1 — 1 Co 0.9 In 0.1 Experiment  7 1 — 1 Co 1 — 0Comparison  8 1 — 1 Co 0.98 In 0.02 Experiment  9 1 — 1 Co 0.95 In 0.05Experiment 10 1 — 1 Co 0.9 In 0.2 Experiment 11 0 Sr 1 Co 0.8 Y 0.1Comparison 12 0.5 Sr 1 Co 0.9 Y 0.1 Experiment 13 0.6 Sr 1 Co 0.9 Y 0.1Experiment 14 0.8 Sr 1 Co 0.9 Y 0.1 Experiment 15 0.9 Sr 1 Co 0.9 Y 0.1Experiment 16 1 — 1 Co 0.9 Y 0.1 Experiment 17 0.9 Sr 1 Co0.8Fe0.14 0.94Y 0.06 Experiment 18 0.9 Sr 1 Co0.8Fe0.1 0.9 Y 0.1 Experiment 19 0.9 Sr1 Co0.7Fe0.1 0.8 Y 0.2 Experiment 20 0 sr 1 Co 0.9 Sn 0.1 Comparison 210.2 Sr 1 Co 0.9 Sn 0.1 Experiment 22 0.5 Sr 1 Co 0.9 Sn 0.1 Experiment23 0.8 Sr 1 Co 0.9 Sn 0.1 Experiment 24 0.9 Sr 1 Co 0.9 Sn 0.1Experiment 25 1 — 1 Co 0.9 Sn 0.1 Experiment Com- Oxygen ponentPermeation No XD rd XE re XF rf Phase Rate  1 — 0 — 0 — 0 X LeakComparison occurs  2 — 0 — 0 — 0 ◯ 1 Experiment  3 — 0 — 0 — 0 ◯ 3Experiment  4 — 0 — 0 — 0 ◯ 3 Experiment  5 — 0 — 0 — 0 ◯ 4.5 Experiment 6 — 0 — 0 — 0 ◯ 4.3 Experiment  7 — 0 — 0 — 0 X impossible Comparisonto measure  8 — 0 — 0 — 0 ◯ 1 Experiment  9 — 0 — 0 — 0 ◯ 4 Experiment10 — 0 — 0 — 0 ◯ 2.5 Experiment 11 — 0 — 0 — 0 X impossible Comparisonto measure 12 — 0 — 0 — 0 ◯ 1 Experiment 13 — 0 — 0 — 0 ◯ 2.5 Experiment14 — 0 — 0 — 0 ◯ 3.5 Experiment 15 — 0 — 0 — 0 ◯ 3.6 Experiment 16 — 0 —0 — 0 ◯ 3.5 Experiment 17 — 0 — 0 — 0 ◯ 3.3 Experiment 18 — 0 — 0 — 0 ◯2.5 Experiment 19 — 0 — 0 — 0 ◯ 1 Experiment 20 — 0 — 0 — 0 X LeakComparison occurs 21 — 0 — 0 — 0 ◯ 1 Experiment 22 — 0 — 0 — 0 ◯ 2.5Experiment 23 — 0 — 0 — 0 ◯ 3.8 Experiment 24 — 0 — 0 — 0 ◯ 3.3Experiment 25 — 0 — 0 — 0 ◯ 3 Experiment

[0195] TABLE 2 1-rc- rd-re- No rba1 XA α XB rf XC rc 26 0.8 Sr 0.98 Co0.9 Sn 0.1 Experiment 27 0.8 Sr 0.95 Co 0.9 Sn 0.1 Experiment 28 0.8 Sr1.02 Co 0.9 Sn 0.1 Experiment 29 0.8 Sr 1.05 Co 0.9 Sn 0.1 Experiment 301 — 1 Co0.85 0.9 In 0.1 Experiment Fe0.05 31 1 — 1 Co0.8 0.9 Sn 0.1Experiment Fe0.1 32 1 — 1 Co0.75 0.85 In0.1 0.15 Experiment Fe0.1 Y0.0533 0.6 Sr 1 Co0.75 0.85 In0.1 0.15 Experiment Fe0.1 Sn0.05 34 0.2 Sr 1Co0.78 0.88 Sn0.01 0.12 Experiment Fe0.1 In0.02 35 0 Sr 1 Co0.7 0.8In0.1 0.2 Comparison Fe0.1 Y0.1 36 0.9 Sr 1 Co 0.85 In 0.1 Experiment 370.9 Sr 1 Co 0.8 In 0.1 Experiment 38 0.9 Sr 1 Co 0.7 In 0.1 Experiment39 0.9 Sr 1 Co 0.7 In 0.1 Experiment 40 0.9 Sr 1 Co 0.85 In 0.1Experiment 41 0.9 Sr 1 Co 0.7 In 0.1 Experiment 42 0.9 La 1 Co 0.85 In0.1 Experiment 43 0.9 La 1 Co 0.85 In 0.1 Experiment 44 0.9 La 1 Co 0.85In 0.1 Experiment 45 0.9 La 1 Co 0.85 In 0.1 Experiment 46 0.8 Sr 1 Co0.8 Y 0.1 Experiment 47 0.8 Sr 1 Co 0.8 Y 0.1 Experiment 48 0.8 Ca 1 Co0.7 Y 0.1 Experiment Oxygen Com- Perme- ponent ation No XD rd XE re XFrf Phase Rate 26 — 0 — 0 — 0 ◯ 3.1 Experiment 27 — 0 — 0 — 0 ◯ 2Experiment 28 — 0 — 0 — 0 ◯ 2.3 Experiment 29 — 0 — 0 — 0 ◯ 1.5Experiment 30 — 0 — 0 — 0 ◯ 3 Experiment 31 — 0 — 0 — 0 ◯ 2.5 Experiment32 — 0 — 0 — 0 ◯ 2.5 Experiment 33 — 0 — 0 — 0 ◯ 2.5 Experiment 34 — 0 —0 — 0 ◯ 1 Experiment 35 — 0 — 0 — 0 X 0.1 Comparison 36 Nb 0.05 — 0 — 0◯ 3.5 Experiment 37 Ta 0.1 — 0 — 0 ◯ 2.6 Experiment 38 Ti 0.2 — 0 — 0 ◯1 Experiment 39 Zr 0.2 — 0 — 0 ◯ 1.2 Experiment 40 — 0 Cu 0.05 — 0 ◯ 2.8Experiment 41 Ta 0.1 Cu 0.1 — 0 ◯ 2 Experiment 42 — 0 Ni 0.05 — 0 ◯ 2.6Experiment 43 — 0 Zn 0.05 — 0 ◯ 2 Experiment 44 — 0 Li 0.05 — 0 ◯ 1.7Experiment 45 — 0 Mg 0.05 — 0 ◯ 2 Experiment 46 — 0 — 0 Al 0.1 ◯ 2.5Experiment 47 — 0 — 0 Ga 0.1 ◯ 2.5 Experiment 48 — 0 — 0 Cr 0.2 ◯ 1Experiment

[0196] TABLE 3 Porous Reactive Porous Catalyst Dense Continuous PorousIntermediate Catalyst layer No. Trash Material Layer Material CatalyticMaterial Active Metal* 01 SrCo_(0.91)Nb_(0.1)O_(3−δ)Ba_(0.5)Sr_(0.5)CO_(0.8) Y_(0.01)Sr_(0.99)Fe_(0.9) Ru Fe_(0.2)O_(3−δ)Nb_(0.1)O_(3−δ) 02 Ba_(0.6)Sr_(0.4)CO_(0.8) SrCo_(0.9)Nb_(0.1)O_(3−δ)SrFe_(0.82)Co_(0.08) Ru + Co + Rh Fe_(0.2)O_(3−δ) Ta_(0.1)O_(3−δ) 03SrCo_(0.9)Ta_(0.1)O_(3−δ) Ba_(0.6)Sr_(0.4)Co_(0.8)SrFe_(0.82)Co_(0.08)Ta_(0.09) Ru + Pd Fe_(0.1)Ta_(0.1)O_(3−δ)Ti_(0.05)Zr_(0.05)O_(3−δ) 04 Ba_(0.6)Sr_(0.4)Co_(0.76)Ba_(0.5)Sr_(0.5)Co_(0.8) Ba_(0.09)Ca_(0.01)Sr_(0.9) Ru + Ni + PtFe_(0.05)Ta_(0.1)Ti_(0.05) Fe_(0.2)O_(3−δ) Fe_(0.87)Nb_(0.1)Zn_(0.01)Zr_(0.05)O_(3−δ) Li_(0.01)Mg_(0.01)O_(3−δ) 05 SrCo_(0.91)Nb_(0.1)O_(3−δ)SrCo_(0.9)Nb_(0.1)O_(3−δ) La_(0.05)Sr_(0.95)Fe_(0.8) NiGa_(0.05)Cr_(0.05)Nb_(0.1)O_(3−δ) 06 SrCo_(0.91)Nb_(0.1)O_(3−δ)SrCo_(0.9)Nb_(0.1)O_(3−δ) BaFe_(0.7)Y_(0.2)Nb_(0.1)O_(3−δ) Ru + Ir 07SrCo_(0.91)Nb_(0.1)O_(3−δ) SrCo_(0.9)Nb_(0.1)O_(3−δ)BaFe_(0.8)Y_(0.1)Ti_(0.1)O_(3−δ) Ru + Re

[0197] TABLE 4 No. Ceramic Membrane Methane Reforming Catalyst 01Ceramic Membrane A Catalyst B 02 Ceramic Membrane B Catalyst B 03Ceramic Membrane C Catalyst A 04 Ceramic Membrane C Catalyst B 05Ceramic Membrane C Catalyst C 06 Ceramic Membrane D Catalyst A 07Ceramic Membrane D Catalyst B 08 Ceramic Membrane D Catalyst C

[0198] TABLE 5 Oxygen Permeation Rate No. Ceramic Membrane Material(cc/min/cm²) 01 BaCO_(0.7)Fe_(0.2)In_(0.1)O_(3−δ) 22 02BaCo_(0.7)Fe_(0.2)Y_(0.1)O_(3−δ) 21 03 BaCo_(0.7)Fe_(0.2)Y_(0.05)O_(3−δ)21

1. A ceramic composition of mixed conducting oxide having substantiallya perovskite structure, said ceramic composition containing: Ba; atleast one kind of element selected from a first group consisting of Coand Fe; at least one kind of element selected from a second groupconsisting of In, Sn and Y, wherein an element selected from the secondgroup is arranged in B site in the perovskite structure.
 2. A ceramiccomposition of mixed conducting oxide having substantially a perovskitestructure, expressed by the following composition formula (formula 1).(Ba_(rba1)XA_(1−rba1))_(α)(XB_(1−rc−rd−re−rf)XC_(rc)XD_(rd)XE_(re)XF_(rf))O_(3−δ)  formula1where XA denotes at least one kind of element selected from a thirdgroup consisting of Sr, Ca and lanthanoide; XB denotes at least one kindof element selected from a first group consisting of Co and Fe; XCdenotes at least one kind of element selected from a second groupconsisting of In, Y, and Sn; XD denotes at least one kind of elementselected from a fourth group consisting of Nb, Ta, Ti, and Zr; XEdenotes at least one kind of element selected from a fifth groupconsisting of Cu, Ni, Zn, Li and Mg; and XF denotes at least one kind ofelement selected from a sixth group consisting of Cr, Ga, and Al, as forthe range of rba1, when XC contains only In, it fulfills the conditionof 0.4≦rba1≦1.0; when XC contains only Y, it fulfills the condition of0.5≦rba1≦1.0; when XC contains only Sn, it fulfills the condition of0.2<rba1≦1.0; and when XC contains two or more elements composing thesecond group, it fulfills the condition of 0.2≦rba1≦1.0, as for therange of rc, when XC contains only Y, it fulfills the condition of0.06≦rc≦0.3; when XC contains at least any one of In or Sn, it fulfillsthe condition of 0.02≦rc≦0.3; the range of rd fulfills the condition of0≦rd≦0.2; the range of re fulfills the condition of 0≦re≦0.2; the rangeof rf fulfills the condition of 0≦rf≦0.2; the range of α fulfills thecondition of 0.9≦α≦1.1, and δ is a value determined to fulfill thecondition of neutral electric charge.)
 3. The ceramic compositionaccording to claim 2, wherein the values of re and rf in saidcomposition formula (formula 1) are both zero.
 4. The ceramiccomposition according to claim 3, wherein rd in said composition formula(formula 1) is zero.
 5. A composite material of catalyst and ceramics,comprising: a selective oxygen-permeable dense continuous layercontaining mixed conducting oxide; a porous intermediate catalyst layercontiguous to a first surface of said dense continuous layer andcontaining mixed conducting oxide; a porous reactive catalyst layercontiguous to said porous intermediate catalyst layer in a manner tosandwich said porous intermediate catalyst layer with said densecontinuous layer, and containing a metal catalyst and a catalystsupport; and a porous catalyst layer contiguous to a second surface ofsaid dense continuous layer and containing mixed conducting oxide. 6.The composite material of catalyst and ceramics according to claim 5,comprising: a multi-layered structure including said porous catalystlayer, said dense continuous layer, said porous intermediate catalystlayer, and said porous reactive catalyst layer; and a porous substratesupporting said multi-layered structure.
 7. The composite material ofcatalyst and ceramics according to claim 5, wherein the composition ofthe mixed conducting oxide contained in at least one layer selected froma group consisting of said dense continuous layer, said porous catalystlayer and said porous intermediate catalyst layer is expressed by thefollowing composition formula (formula 2).(Ln_(1−rg−rba3)XG_(rg)Ba_(rba3))(XH_(rh)XI_(ri)XJ_(rj))O_(3−δ)  (formula2)(where Ln denotes at least one kind of element selected fromlanthanoide; XG denotes at least one kind of element selected from aseventh group consisting of Sr and Ca; XH denotes at least one kind ofelement selected from an eighth group consisting of Co, Fe, Cr, and Ga,in which the sum total of the number of moles of Cr and Ga is 0 to 20%to the sum total of the number of moles of the elements composing theabove-described eighth group; XI denotes at least one kind of elementselected from a ninth group consisting of Nb, Ta, Ti, Zr, In and Y,including at least one kind of element selected from a tenth groupconsisting of Nb, Ta, In, and Y; and XJ denotes at least one kind ofelement selected from an eleventh group consisting of Zn, Li and Mg, asfor the range of rba3: when XI contains only In, it fulfills thecondition of 0.4≦rba3≦1.0; when XI contains only Y, it fulfills thecondition of 0.5≦rba3≦1.0; and when XI contains only In and Y, itfulfills the condition of 0.2≦rba3≦1.0, the range of “rg+rba3” fulfillsthe condition of 0.8≦rg+rba3≦1, the range of rh fulfills the conditionof 0<rh, the range of ri fulfills the condition of 0<ri≦0.5, the rangeof rj fulfills the condition of 0≦rj≦0.2, and the range of “rh+ri+rj”fulfills 0.98≦rh+ri+rj≦1.02, and δ is a value determined to fulfill thecondition of neutral electric charge.)
 8. The composite material ofcatalyst and ceramics according to claim 7, wherein a composition ofmixed conducting oxide composing at least one layer selected from agroup consisting of said dense continuous layer and said porous catalystlayer is expressed by the composition formula (formula 2); and whereinsaid porous intermediate catalyst layer contains at least one kind ofelement selected from a twelfth group consisting of Co, Fe, Mn, and Pd.9. The composite material of catalyst and ceramics according to claim 5,wherein porosity of said porous catalyst layer and said porousintermediate catalyst layer is 20 to 80%, the thickness of said densecontinuous layer is 1 μm to 2 mm, said catalyst support contains MgO,and said metal catalyst uses at least one kind of element selected froma thirteenth group consisting of Ni, Co, Ru, Rh, Pt, Pd, Ir and Re as anactive metal kind.
 10. The composite material of catalyst and ceramicsaccording to claim 5, wherein said porous intermediate catalyst layer isformed by sintering a material particle of 10 μm or less in particlediameter on said dense continuous layer at 950° C. or more; and whereinsaid porous reactive catalyst layer is formed by sintering a materialparticle of 10 μm or less in particle diameter on said porousintermediate catalyst layer at 950° C. or more.
 11. A membrane reactor,comprising the composite material of catalyst and ceramics according toclaim
 5. 12. A composite material of catalyst and ceramics comprising: adense ceramic membrane of which composition is expressed by thefollowing composition formula (formula 2), containing mixed conductingoxide having a perovskite structure; and a catalyst portion contiguousto a first surface of said dense ceramic membrane and containingmagnesia and Ni.(Ln_(1−rg−rba3)XG_(rg)Ba_(rba3))(XH_(rh)XI_(ri)XJ_(rj))O_(3−δ)  (formula2) (where Ln denotes at least one kind of element selected fromlanthanoide; XG denotes at least one kind of element selected from aseventh group consisting of Sr and Ca; XH denotes at least one kind ofelement selected from an eighth group consisting of Co, Fe, Cr, and Ga,in which the sum total of the number of moles of Cr and Ga is 0 to 20%to the sum total of the number of moles of the elements composing theabove-described eighth group; XI denotes at least one kind of elementselected from the ninth group consisting of Nb, Ta, Ti, Zr, In and Y,including at least one kind of element selected from the tenth groupconsisting of Nb, Ta, In, and Y; and XJ denotes at least one kind ofelement selected from an eleventh group consisting of Zn, Li and Mg, asfor the range of rba3: when XI contains only In, it fulfills thecondition of 0.4≦rba3≦1.0; when XI contains only Y, it fulfills thecondition of 0.5≦rba3≦1.0; and when XI contains only In and Y, itfulfills the condition of 0.2≦rba3≦1.0, the range of “rg+rba3” fulfillsthe condition of 0.8≦rg+rba3≦1, the range of rh fulfills the conditionof 0≦rh, the range of ri fulfills the condition of 0≦ri≦0.5, the rangeof rj fulfills the condition of 0≦rj≦0.2, and the range of “rh+ri+rj”fulfills 0.98≦rh+ri+rj≦1.02, and δ is a value determined to fulfill thecondition of neutral electric charge.)
 13. The composite material ofcatalyst and ceramics according to claim 12, comprising: a porous layerbeing contiguous to a second surface of said dense ceramic membrane, andincluding mixed conducting oxide having a perovskite structure, whereinthe composition of said porous layer is expressed by the compositionformula (formula 2).
 14. The composite material of catalyst and ceramicsaccording to claim 13, wherein the porosity of said porous layer is 20to 80%, and the thickness of said porous layer is 0.001 to 5 mm.
 15. Thecomposite material of catalyst and ceramics according to claim 12,wherein the value of rba3 in the composition formula (formula 2) is 1.0.16. The composite material of catalyst and ceramics according to claim12, wherein said catalyst portion contains a composition expressed bythe following composition formula (formula 6).Ni_(rni)Mn_(rmn)Mg_(1−rni−rmn) O_(c)  (formula 6)(wherein the range ofrni fulfills the condition of 0<rni≦0.4 while the range of rmn fulfillsthe condition of 0≦rmn≦0.1, and c is a value determined to fulfill thecondition of neutral electric charge.)
 17. The composite material ofcatalyst and ceramics according to claim 16, wherein said catalystportion contains at least one kind of element selected from a fourteenthgroup consisting of Ru, Rh, Pd, Re, Os, Ir, and Pt.
 18. The compositematerial of catalyst and ceramics according to claim 12, wherein saidcatalyst portion contains magnesia, Ni, and Mn.
 19. The compositematerial of catalyst and ceramics according to claim 18, wherein saidcatalyst portion contains at least one kind of element selected from thefourteenth group consisting of Ru, Rh, Pd, Re, Os, Ir, and Pt.
 20. Thecomposite material of catalyst and ceramics according to claim 12,wherein said catalyst portion contains composite oxide expressed by thecomposition formula (formula 2).
 21. The composite material of catalystand ceramics according to claim 12, comprising: a multi-layeredstructure provided with said dense ceramic membrane and said catalystportion; and a porous substrate supporting said multi-layered structure.22. The composite material of catalyst and ceramics according to claim13, comprising; a multi-layered structure provided with said porouslayer, said dense ceramic membrane and said catalyst portion; and aporous substrate supporting said multi-layered structure.
 23. Thecomposite material of catalyst and ceramics according to claim 12,wherein said catalyst portion includes a porous layer having an averagepore diameter of 10 μm or less, and thickness of 0.01 to 1 mm.
 24. Thecomposite material of catalyst and ceramics according to claim 12,comprising: a reforming catalyst portion contiguous to said catalystportion in a manner to sandwich said catalyst portion between said denseceramic membrane and the reforming catalyst portion, and adjusted inparticle size to be 0.5 mm or more.
 25. The composite material ofcatalyst and ceramics according to claim 12, wherein the thickness ofsaid dense ceramic membrane is 0.5 to 2 mm.
 26. The composite materialof catalyst and ceramics according to claim 25, comprising: a reformingcatalyst portion contiguous to said catalyst portion in a manner tosandwich said catalyst portion between said dense ceramic membrane andthe reforming catalyst portion, and particle size adjusted to be 0.5 mmor more of the particle size.
 27. The composite material of catalyst andceramics according to claim 24, wherein said reforming catalyst portioncontains a composition expressed by the following composition formula(formula 6). Ni_(rni)Mn_(rmn)Mg_(1−rni−rmn)O_(c)  (formula 6)(whereinthe range of rni fulfills the condition of 0<rni≦0.4 while the range ofrmn fulfills the condition of 0≦rmn≦0.1, and c is a value determined tofulfill the condition of neutral electric charge.)
 28. The compositematerial of catalyst and ceramics according to claim 27, wherein saidreforming catalyst portion contains at least one kind of elementselected from the fourteenth group consisting of Ru, Rh, Pd, Re, Os, Ir,and Pt.
 29. The composite material of catalyst and ceramics according toclaim 24, wherein said reforming catalyst portion contains magnesia, Ni,and Mn.
 30. The composite material of catalyst and ceramics according toclaim 29, wherein said reforming catalyst portion contains at least onekind of element selected from the fourteenth group consisting of Ru, Rh,Pd, Re, Os, Ir, and Pt.
 31. The composite material of catalyst andceramics according to claim 24, wherein said reforming catalyst portioncontains at least one kind of element selected invariably containing Nior Ru from the fifteenth group consisting of Ni, Ru, Rh, Pd, Re, Os, Irand Pt.
 32. A production method of synthetic gas, comprising the stepsof: making an atmosphere, to a membrane provided with a dense ceramicmembrane and a catalyst portion contiguous to a first surface of saiddense ceramic membrane, on said catalyst portion side of the partitionmembrane to be a hydrocarbon-containing gas atmosphere and on the denseceramic membrane side to be an oxygen-containing gas atmosphere, whereinsaid dense ceramic membrane contains perovskite structured mixedconducting oxide; and said catalyst portion contains magnesia and Ni.(Ln_(1−rg−rba3)XG_(rg)Ba_(rba3))(XH_(rh)XI_(ri)XJ_(rj))O_(3−δ)  (formula2) (where Ln denotes at least one kind of element selected fromlanthanoide; XG denotes at least one kind of element selected from aseventh group consisting of Sr and Ca; XH denotes at least one kind ofelement selected from an eighth group consisting of Co, Fe, Cr, and Ga,in which the sum total of the number of moles of Cr and Ga is 0 to 20%to the sum total of the number of moles of the elements composing theabove-described eighth group; XI denotes at least one kind of elementselected from the ninth group consisting of Nb, Ta, Ti, Zr, In and Y,including at least one kind of element selected from the tenth groupconsisting of Nb, Ta, In, and Y; and XJ denotes at least one kind ofelement selected from an eleventh group consisting of Zn, Li and Mg, asfor the range of rba3: when XI contains only In, it fulfills thecondition of 0.4≦rba3≦1.0; when XI contains only Y, it fulfills thecondition of 0.5≦rba3≦1.0; and when XI contains only In and Y, itfulfills the condition of 0.2≦rba3≦1.0, the range of “rg+rba3” fulfillsthe condition of 0.8≦rg+rba3≦1, the range of rh fulfills the conditionof 0<rh, the range of ri fulfills the condition of 0<ri≦0.5, the rangeof rj fulfills the condition of 0≦rj≦0.2, and the range of “rh+ri+rj”fulfills 0.98≦rh+ri+rj≦1.02, and δ is a value determined to fulfill thecondition of neutral electric charge.)
 33. The production method ofsynthetic gas according to claim 32, wherein the step of making theatmosphere on the catalyst portion side of said partition membrane to bea hydrocarbon-containing atmosphere includes a step of making saidcatalyst portion side atmosphere to be a methane-containing gasatmosphere having a pressure of 0.3 MPa or more, wherein said catalystportion includes a porous layer having an average pore size of 10 μm orless, and a thickness of 0.01 to 1 mm.
 34. The production method ofsynthetic gas according to claim 32, wherein the step of making theatmosphere on the catalyst portion side of said partition membrane to bea hydrocarbon-containing gas atmosphere includes a step of making saidcatalyst portion side atmosphere to be a methane-containing gasatmosphere having a pressure of 0.5 MPa or less, wherein said catalystportion includes a porous layer having an average pore size of 10 μm orless, and a thickness of 0.01 to 1 mm, wherein said partition membraneincludes a reforming catalyst portion contiguous to said catalystportion in a manner to sandwich said catalyst portion between said denseceramic membrane and the reforming catalyst portion, and adjusted inparticle size to be 0.5 mm or more.
 35. The production method ofsynthetic gas according to claim 32, wherein the step of making theatmosphere on said catalyst portion side of the partition membrane to bea hydrocarbon-containing gas atmosphere, comprising the steps of: makingthe atmosphere of said catalyst portion side to be a methane-containinggas atmosphere; and forcing water vapor to contain into themethane-containing gas from outside to adjust a ratio of concentrationof the water vapor to methane to 2 or less.
 36. The production method ofsynthetic gas according to claim 32, wherein said methane-containing gasincludes: one kind of recycle gas selected from a group consisting ofnatural gas, coalfield gas, coke-oven gas, and gas obtained byFischer-Tropsch synthetic reaction, or, one kind of reforming gasselected from a group consisting of natural gas, coalfield gas,coke-oven gas, LPG, naphtha, gasoline, and kerosene.
 37. A productionapparatus of synthetic gas, comprising a partition membrane, saidpartition membrane having: a dense ceramic membrane containing mixedconducting oxide of which composition is expressed by the followingcomposition formula (formula 2), and having a perovskite structure; anda catalyst portion contiguous to a first surface of said dense ceramicmembrane and containing magnesia and Ni.(Ln_(1−rg−rba3)XG_(rg)Ba_(rba3))(XH_(rh)XI_(ri)XJ_(rj))O_(3−δ)  (formula2) (where Ln denotes at least one kind of element selected fromlanthanoide; XG denotes at least one kind of element selected from aseventh group consisting of Sr and Ca; XH denotes at least one kind ofelement selected from an eighth group consisting of Co, Fe, Cr, and Ga,in which the sum total of the number of moles of Cr and Ga is 0 to 20%to the sum total of the number of moles of the elements composing theabove-described eighth group; XI denotes at least one kind of elementselected from the ninth group consisting of Nb, Ta, Ti, Zr, In and Y,including at least one kind of element selected from the tenth groupconsisting of Nb, Ta, In, and Y; and XJ denotes at least one kind ofelement selected from an eleventh group consisting of Zn, Li and Mg, asfor the range of rba3: when XI contains only In, it fulfills thecondition of 0.4≦rba3≦1.0; when XI contains only Y, it fulfills thecondition of 0.5≦rba3≦1.0; and when XI contains only In and Y, itfulfills the condition of 0.2≦rba3≦1.0, the range of “rg+rba3” fulfillsthe condition of 0.8≦rg+rba3≦1, the range of rh fulfills the conditionof 0<rh, the range of ri fulfills the condition of 0<ri≦0.5, the rangeof rj fulfills the condition of 0<rj≦0.2, and the range of “rh+ri+rj”fulfills 0.98≦rh+ri+rj≦1.02, and δ is a value determined to fulfill thecondition of neutral electric charge.)
 38. A method for activating acatalyst comprising the step of: making an atmosphere, to a partitionmembrane provided with a dense ceramic membrane of which crystalstructure is a perovskite structure and a catalyst portion contiguous toa first surface of said dense ceramic membrane and containing acomposition expressed by the following composition formula (formula 6),on said catalyst portion side of the partition membrane to be amethane-containing gas atmosphere having a pressure of 0.3 MPa or more,and on said dense ceramic membrane side to be an oxygen-containing gasatmosphere. Ni_(rni)Mn_(rmn)Mg_(1−rni−rmn)O_(c)  (formula 6) (whereinthe range of rni fulfills the condition of 0<rni≦0.4 while the range ofrmn fulfills the condition of 0≦rmn≦0.1, and c is a value determined tofulfill the condition of neutral electric charge.)